PAUL MARTIN
The Sickening Mind
Brain, Behaviour, Immunity and Disease

COPYRIGHT

William Collins

An imprint of HarperCollinsPublishers 1 London Bridge Street London SE1 9GF

www.harpercollins.co.uk

This edition published by HarperPress 2005

First published in the UK by HarperCollinsPublishers, 1997

Copyright © Paul Martin, 1997

Paul Martin has asserted the moral right to be identified as the author of this work

The author and publishers are grateful to the following for permission to reproduce material: International Music Publications Limited, for ‘Sex and Drugs and Rock and Roll’ by Ian Drury and Chas Jankel, © 1977 Temple Mill Music Ltd, Warner/Chappell Music Ltd; Hall, J.G., ‘Emotion and immunity’ Lancet, 2, 326–327, © The Lancet Ltd., (1985); extracts from Riceyman Steps by Arnold Bennett by permission A. P. Watt Ltd., on behalf of Mme V. Eldin; extracts from The Man with the Golden Gun by Ian Fleming by permission Glidrose Publications Ltd, © Glidrose Productions Ltd 1965; extract from Three Men in a Boat by Jerome K. Jerome by permission A. P. Watt Ltd., on behalf of The Society of Authors Ltd.; extracts from Down and Out in Paris and London by George Orwell by permission A. M. Heath & Co. Ltd, copyright © The Estate of the late Sonia Brownell Orwell and Martin Secker and Warburg Ltd; extract from Death of a Salesman by Arthur Miller by permission Reed Publishers, © Arthur Miller 1949; extract from ‘Do not go gentle into that good night’ from The Poems by Dylan Thomas by permission David Higham Associates: originally published by J. M. Dent; Thanks also to Harriet Wasserman Literary Agency Inc., for permission to quote from Seize the Day by Saul Bellow; Macmillan General Books, for Jude the Obscure and The Mayor of Casterbridge by Thomas Hardy. Every reasonable effort has been made to contact copyright holders for all the extracts reproduced in this volume. However, it has not been possible to make contact with all copyright holders. The author and publishers would ask, therefore, that any copyright holder who feels a quotation contained herein may contravene their copyright contact HarperCollinsPublishers at the address above.

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CONTENTS

COVER

TITLE PAGE

COPYRIGHT

1 The Body of Knowledge

Opening shots

Iraqi SCUDs and Chinese grandmothers

Roundheads and Cavaliers

Some completely fictitious case histories

Invisible worms

Chronic fatigue syndrome

2 Shadows on the Sun

Death, disaster and voodoo

Trouble, strife and sickness

Life events

The mind and the common cold

3 Psyche’s Machine: The Inside Story

The perception of sickness

Bad behaviour

Mind over immune matter

Understanding immunity

Autoimmunity

Measuring immunity

The mind – immunity connections

4 Mind and Immunity

What can the mind do to the immune system?

Bereavement and nuclear disasters

Spaceflight, exams and other nastiness

Does it matter?

What can the immune system do to the mind?

Depression

Immune conditioning

Immune conditioning and disease

Some allergic history revisited

The strange story of the left-handed brain

The wonderful world of herpes

5 The Demon Stress

What is stress?

The biology of stress

Stress, immunity and health

The quality of stress

Control, control and control

The joy of stress

The stress-seekers

6 Other People

Hell is other people? – relationships as stressors

Hell is alone? – the harmful effects of isolation

Michael Henchard’s will

How does it work?

Social relationships and immunity

The lonely future

7 The Wages of Work

The toad work

Who suffers and why?

The scourge of unemployment

8 Sick at Heart

Hearts and minds

The mind in sudden cardiac death and heart disease

Coronary-prone personalities and heart disease

The Type A behaviour pattern

Type A – the evidence

Anger and hostility

How does it work?

Biological reactivity and the Type A person

9 The Mind of the Crab

The mind in cancer

Is there a cancer-prone personality?

Some fictional Type Cs

Psychological influences on survival

How does it work?

10 Encumbered with Remedies

Relax!

Exercise!

Those little pink pills

Psychoneuroimmunology and AIDS

Imagery, miracle cures and other exotica

Kill or cure?

11 Exorcising the Ghost in the Machine

That old mind – body problem

The grip of dualism

Some ancient history

René Descartes and the separation of mind from body

Descartes’ demise

12 A Fresh Pair of Lenses

Development

Mothers and offspring

Evolution

Sick by design

Genes for disease

Diseases of modern life

Evolutionary arms races

The functions of unpleasantness

Why does stress make us ill?

Darwin’s illness

Parting shots

KEEP READING

REFERENCES

INDEX

ACKNOWLEDGMENTS

ABOUT THE AUTHOR

NOTES

PRAISE

ABOUT THE PUBLISHER

1 The Body of Knowledge

Most of the time we think we’re sick, it’s all in the mind.

Thomas Wolfe, Look Homeward, Angel (1929)

It is time to acknowledge that our belief in disease as a direct reflection of mental state is largely folklore.

Editorial, New England Journal of Medicine (1985)

Opening shots

You, dear reader, are going to die. Not for a long time, I hope, and painlessly. But die you undoubtedly will. And unless you die in the near future, and from unnatural causes, you will be ill before you die – probably several times. Some remarkable scientific discoveries have shown that your mind will affect your susceptibility to those illnesses and may have a substantial bearing on the nature and timing of your eventual death.

This book is about these scientific discoveries. It explores the ways in which your psychological and emotional state influence your physical health and how, in turn, your physical state affects your mind. It seeks to explain some of the extraordinary things that scientists have discovered in recent years about the interconnections between the brain, behaviour, immunity and health. By unravelling the biological mechanisms that underlie these phenomena, scientists can at last reconcile many commonplace notions about mental influences on health with a modern understanding of how the brain and behaviour affect the functioning of the body.

This is not intended to be a self-help book and I shall not be setting out detailed prescriptions for instant health or miracle cures for AIDS. The rapidly growing corpus of scientific knowledge about mind – body interactions has numerous potentially valuable applications in medicine, and I shall describe them. But practical action must be built on solid foundations of knowledge and understanding. As Sir Francis Bacon once remarked, ‘Knowledge itself is power.’

Bacon also remarked that ‘all knowledge and wonder (which is the seed of knowledge) is an impression of pleasure in itself.’ I hope you will find the discoveries described here intriguing and worthwhile in their own right, regardless of their utilitarian value. We neglect the sheer wonder of scientific knowledge at our peril. Practical applications matter a great deal, but they are not the only fruits of science.

Let us get down to business by conducting a simple thought experiment. When you have read this paragraph shut your eyes and cast your mind back to the most mortifyingly embarrassing moment in your life, the worst that you can dredge up from the dank recesses of your memory. Think hard and choose the most awful, squirm-inducing calamity. Be brutally honest. Perhaps you committed an appalling social blunder at an august gathering, or said exactly the wrong thing at the wrong time. Close your eyes and re-live the incident in all its ghastliness, focusing on your own humiliation.

Have you blushed? Are your cheeks burning with embarrassment? If so, you have just demonstrated a mundane example of an important biological principle: that mere thoughts and emotions can generate very real physical reactions.

If you would like to demonstrate the empirical truth of this principle again, but in a different and more recreational way, close your eyes and conjure up your most arousing and succulent sexual fantasy. You surely must have one. Sit back and let your mind savour the luscious details of whatever erotic images it has chosen. Let the moist, quivering images run rampant. The physical consequences of what is now going on in your mind should, with any luck, be more fun than a blush.

The mind’s influence on the body is usually more serious than a blush or a sexual frisson, however. It can even determine when we die. As an appetizer we shall consider two examples.

Iraqi SCUDs and Chinese grandmothers

During the Gulf War of 1991 Iraq launched a series of missile attacks against Israel. Many Israeli civilians died as a result of these attacks. But the vast majority of them did not die from any direct physical effects of the missiles. They died from heart failure brought on by the fear, anxiety and stress associated with the bombardment. They died because of what was going on in their minds.

How do we know this? After the war was over Israeli scientists analysed the official mortality statistics and found something remarkable. There had been a large and anomalous jump in the death rate among Israeli citizens on one particular day: the day of the first Iraqi attacks.

In the early hours of 18 January 1991 Iraq launched the first of several SCUD missile attacks against Israeli cities. Measured in terms of physical destruction, the Iraqi weapons were surprisingly ineffective. There were no deaths through physical injuries in the first attack and only two people were killed by the direct physical effects of SCUD detonations during the subsequent sixteen days on which missiles fell. And yet, on the day of the first attack, the death rate in Israel leapt by 58 per cent. A total of 147 deaths were reported, 54 more than would have been expected on the basis of previous mortality figures for that time of year. In statistical terms this was a highly significant increase; the odds against it arising from random fluctuations alone were enormous. What happened?

The evidence consistently pointed towards one conclusion: the sharp rise in death rate on 18 January 1991 was primarily a consequence of severe emotional stress brought on by fear of the Iraqi bombardment. It was the psychological impact of the SCUD missiles, not their physical impact, that claimed the majority of the victims.

The reasoning behind this conclusion was straightforward. The unexpected ‘extra’ deaths resulted in the main from heart failure or other forms of abrupt cardiovascular catastrophe. There was no increase in deaths from lingering diseases such as cancer, for example. As we shall see later, psychological stress can induce physiological changes which may prove fatal to someone who already has a diseased heart or clogged coronary arteries.

The ‘extra’ deaths were concentrated in areas of Israel where the levels of fear and anxiety were highest: regions that were known to be threatened by Iraqi missiles. In parts of Israel where SCUDs were not expected to land the mortality rate remained much the same as usual. Psychological studies carried out during this period indicated that the most stressful time for Israeli citizens was the few days leading up to the outbreak of war on 17 January, peaking on the day of the first SCUD missile attacks. There was enormous and well-founded concern about possible Iraqi use of chemical and biological weapons. The entire Israeli population had been issued with gas masks and automatic atropine syringes in case of chemical attack, and every household had been told to prepare a sealed room.¹

After the first Iraqi strike had occurred, and turned out to be less cataclysmic than feared, there was a marked decline in levels of stress. As in other wars, the populace adapted to the situation with surprising speed. Then, as the fear and anxiety subsided, so the death rate also began to decline. There were seventeen further Iraqi missile attacks over the following weeks, but Israeli mortality figures over this period were no higher than average.

There is little doubt that many of the Israelis who died in the opening days of the war were killed by the Iraqi missiles. But there is equally little doubt that many of them died because of what was going on in their minds and not from physical injuries. Of course, their mental state was not the only thing that contributed to their deaths. Most, if not all, of those who died also had a pre-existing medical problem which made them especially vulnerable to the damaging effects of psychological stress. Many died because they had pre-existing coronary heart disease and their hearts gave out under the stress.

One of the recurring themes in this book is the simple point that disease and death seldom have single causes. The mind can help to precipitate illness or death, but this does not mean that bacteria, viruses, cancer cells, clogged arteries and other all-too-solid agents of disease are not also involved.

Mortality statistics have revealed another fascinating phenomenon. Psychological factors can not only hasten death, as happened during the Gulf War, they can also postpone it. There is less likelihood of a person dying on the eve of an occasion that has symbolic significance for them, such as an important religious festival or birthday. There is compelling evidence that individuals on the verge of death can postpone their death for a few days until the special occasion has passed.

A clear demonstration of this phenomenon came from some scrupulously designed research conducted by David Phillips and Daniel Smith of the University of California at San Diego. They analysed the mortality statistics for Chinese people living in California to see whether there were any fluctuations in the risk of dying at around the time of the Harvest Moon Festival – an occasion which is of symbolic importance to Chinese people but not others.

Phillips and Smith found a large and statistically significant dip in the number of Chinese dying from natural causes just before the Harvest Moon Festival. This was followed by a corresponding and compensatory rise in mortality just after the festival was over. In the week preceding the festival the death rate among Chinese Californians was 35 per cent below the expected level, while in the week after the festival it was 35 per cent higher than expected. There was no overall change in the number of people dying, but some deaths that would otherwise have occurred just before the festival were somehow postponed until after it was over.

There is little doubt that this strange phenomenon of delayed death was specifically linked to the symbolic occasion of the Harvest Moon Festival. The dip and rise in the risk of dying was most evident among elderly Chinese women, who play a central role in the ceremonies. The Harvest Moon Festival is a movable feast – the date varies somewhat from year to year – so the fluctuation in mortality rate was definitely linked to the occasion itself, rather than to any specific calendar date. Furthermore, there were no comparable fluctuations in mortality among Jews and other non-Chinese Californians for whom the Harvest Moon Festival has no symbolic importance.

The analysis only looked at deaths from natural causes, so the phenomenon could not be explained by changes in people’s propensity to commit suicide. Conceivably, some deaths might have been delayed because sick individuals took better care of themselves in the run-up to the festival, or because they received extra attention from their family and doctor. But the sheer scale of the phenomenon implied that something more profound was going on as well. In fact, the biggest fluctuations were in deaths caused by disorders of the heart and circulatory system, especially strokes and heart attacks. These are notoriously susceptible to psychological and emotional influences.

An almost identical dip and rise in mortality rate occurs among Jewish people around the festival of Passover. Like the Harvest Moon Festival, Passover is of cultural significance for one section of the community only and its dates vary from year to year.

The statistics reveal that the number of Jewish people dying from natural causes dips sharply just before Passover and bounces back with a compensatory increase immediately afterwards. Again, the fluctuation relates primarily to strokes and heart attacks and no such variation in mortality occurs among non-Jews for whom Passover has no personal significance.

Evidence like this strongly implies the existence of links between our mental or emotional state and our physical health. It is the scientific nature of these mind – body links, and their many ramifications, that we shall be exploring in this book.

Roundheads and Cavaliers

All scientists know of colleagues whose minds are so well equipped with the means of refutation that no new idea has the temerity to seek admittance. Their contribution to science is accordingly very small.

Peter Medawar, A Note on ‘The Scientific Method’ (1949)

I am too much of a sceptic to deny the possibility of anything.

T. H. Huxley, letter to Herbert Spencer (1886)

Contemporary attitudes towards the relationships between mind, body and disease are strangely confused. On the one hand we have the uncritical acceptance by the public, popular media and gurus of New Age medicine that the mind is both the source and the remedy for the majority of bodily ills. Set against these Cavaliers of mind – body interactions we have the Roundhead sceptics, who either dismiss the connections between psychological factors and physical disease as pseudo-scientific wishful thinking, or else simply ignore them altogether.

The tenet that psychological factors play a role in causing or curing bodily diseases is, of course, an ancient one – far older than modern medicine. Throughout history people have held deep-seated beliefs in the power of the mind to influence physical health, and down the centuries (until the twentieth century, anyway) physicians have explicitly linked physical wellbeing with mental wellbeing. It therefore comes as no great surprise to us if a major emotional upset such as bereavement, depression, divorce or redundancy later manifests itself in physical form. Our everyday experience, let alone statistical data from the Gulf War, seems to support this view.

But is this age-old notion of the mind affecting physical health a self-evident truth or merely unsubstantiated pseudo-science? Is it true that we are more likely to fall ill when we are stressed, anxious or depressed? Are individuals with certain personality types more susceptible to colds, allergies, heart disease or cancer? These are questions of profound medical significance. They are also fascinating scientific puzzles.

In ancient times healers worked on the pragmatic basis that the mind and the body are intertwined. Physical disorders could stem from problems in the mind and mental disorders could be reflections of bodily disease. Accordingly, physicians were encouraged to treat the soul and not just the body, using soothing words to comfort the patient’s mind.

Ancient Greek medicine placed great emphasis on the curative power of katharsis – the purging and purification of the patient’s soul. Plato and other great thinkers recognized that these psychological charms were remarkably effective in relieving physical ailments. They also recognized that these charms would not work properly unless both the patient and the physician believed in their curative powers.

Nowadays the supposedly damaging effects on health of anxiety, over-work, job insecurity and loneliness form a recurrent theme in the media, which preaches the message that stress makes us ill. The implicit connection between mental state and physical health seems to be uncritically accepted by an increasingly health-conscious public.

There has been an explosive growth in alternative and complementary forms of medicine, which tend to emphasize the underlying unity of mind and body. Around one third of the adult population has consulted a practitioner of the alternative medical arts at some time. Bookshop shelves groan under the weight of publications proclaiming the self-help gospel that health is all a matter of thinking the right thoughts and banishing negative emotions.

The self-help industry and New Age gurus offer us such tantalizing prospects as self-healing through love, thinking ourselves better from cancer, using the mind to heal all manner of dread diseases and, ultimately, reaching that holistic nirvana of health, happiness and self-fulfilment through the power of pure thought. It is easy to see why the sceptical Roundheads can be so dismissive of the mind – body Cavaliers.

A profound change in the pattern of diseases during the twentieth century may also have contributed to this trend. The infectious diseases that killed vast numbers until fifty years ago have almost disappeared from the wealthy industrialized nations – though not from poorer parts of the world. Their place in the league table has been taken by chronic degenerative disorders such as coronary heart disease and cancer. Diseases of the heart and circulatory system, cancer and accidental injuries now account for more than three-quarters of all deaths. In contrast, infectious and parasitic diseases account for less than 0.5 per cent of all deaths.²

The causal factors that contribute to these modern-day killers are much more complex than the relatively understandable causes of infectious diseases. We all recognize that tuberculosis is caused by bacteria, but cancer and heart disease are altogether more obscure. It is therefore easier to believe that the mind may play a role in their genesis. Factors as diverse as tobacco, red meat, slothfulness, insufficient fibre, childlessness, salt, pesticides, sunburn and radiation can cause serious diseases, so why not psychological stress or depression?

But is there any scientific basis for these beliefs? Just because people have always assumed something to be true does not make it so. After all, the earth was at one time assumed to be flat, stationary and at the centre of the universe. This belief appeared to be supported by everyday experience and was universally accepted as a self-evident truth. Yet it turned out to be completely wrong. Folklore, faith and dogma are not always reliable guides.

In stark contrast to the popular attitudes we have the inherent scepticism harboured by many scientists and doctors towards the notion that mere thoughts or emotions could possibly have an impact on such brutally physical processes as viral infections, coronary heart disease or cancer.

Scientific research in this field has often been tinged with a largely undeserved aura of crankiness. ‘Psychosomatic’ phenomena carry with them a whiff of self-indulgent fantasy, along with the implication that they lack both substance and scientific respectability. The suggestion that psychological and emotional factors play a causal role in disease is often regarded as an admission that the real (i.e., physical) origins of the disease are not yet understood. As Susan Sontag put it in her 1978 book Illness as Metaphor: ‘Theories that diseases are caused by mental states and can be cured by will power are always an index of how much is not understood about the physical terrain of a disease.’

The belief in an intimate connection between mental state and physical health has had a decidedly rocky history in Western medicine, despite its promising beginnings in the civilizations of China and Greece more than two thousand years ago. By the end of the nineteenth century the overwhelmingly predominant approach to medicine was to focus exclusively on the disease and its identifiable physical causes, such as bacteria. Medical research could get to grips with bacteria, but thoughts and emotions were altogether too ethereal. The patient’s mental state increasingly came to be seen as an embarrassing irrelevance – the province of psychologists and other faintly disreputable types rather than a proper concern of scientific medicine. In later chapters we shall consider why the mind and body came to be separated in Western thought, and how this estrangement of psyche from soma has had such an all-pervasive influence on modern science and medicine.

Yet even in the late nineteenth century there were notable exceptions to this rule. For instance, in 1884 Daniel Hack Tuke, one of the pioneers of British psychiatry, published the second edition of a work entitled Illustrations of the Influence of the Mind Upon the Body in Health and Disease, Designed to Elucidate the Action of the Imagination. In it, Tuke argued that the mind and body are inextricably linked through physiological processes; and that our mental state consequently affects our physical health and vice versa. State-of-the art research in the closing years of the twentieth century has come to much the same conclusion – and not before time.

History shows that important ideas can be ignored even if there is good evidence to support them. It is worth recalling the uncomfortable fact that compelling scientific evidence for the connection between smoking, disease and death was available for many years before it started to be taken seriously. Nowadays the link between smoking and all manner of dread diseases is almost universally accepted. Yet this was not always so. Scientists had suspected that smoking was bad for health long before the first solid evidence for a connection with lung cancer was published in 1950. During the 1950s and 1960s a succession of studies concluded that smoking increases the risks of lung cancer, heart disease and a host of other life-threatening conditions. Nevertheless, governments, the general public and even doctors remained sceptical of these links, and two decades passed before the research started to have an impact.

Contemporary physicians and scientists frequently dismiss the idea that the mind has a profound effect on physical health. To quote an editorial from a prestigious international medical journal: ‘we have been too ready to accept the venerable belief that mental state is an important factor in the cause and cure of disease.’ Another sceptic, also writing in a leading medical publication, comments that ‘Mental stress is frequently blamed for the generation of organic disease, especially if it is of uncertain or complex aetiology, though without reliable or confirmatory argument … The morbidity of mental stress is commonly widely exaggerated.’ Or consider this trenchant counterblast from a third scientific sceptic:

During the last quarter of the 19th century many medical men asserted confidently that the stress of ‘modern’ life (i.e., all that gadding about in hansom cabs, paddle steamers, and railway trains) caused general paralysis of the insane [the final stages of syphilis]. Most of us now accept that this view was mistaken. I think that the notion that emotional factors have an important bearing on immunity, or on the cause or progress of cancer, comes into the same category.

In many respects the scientific evidence for connections between psychological factors and disease is stronger and more consistent than the evidence for certain other medical risk factors which are, nonetheless, regarded as less controversial. The putative links between dietary salt or cholesterol and heart disease are viewed with nothing like the same degree of suspicion and scepticism as psychological risk factors. Yet the scientific evidence that excessive salt or cholesterol in the diet actually cause heart disease in normal people is by no means conclusive. On the other hand, the evidence that psychological factors contribute to heart disease is wide-ranging and convincing, as we shall see later. There is a curious double standard at work here.

The fact is that most people, doctors and scientists included, find it inherently easier to believe in the reality of apparently simple physical causes of disease (such as cholesterol, salt, bacteria or viruses) than to accept that mere thoughts or emotions can affect our health. Partly as a result of such sceptical attitudes, research into the connections between the brain, behaviour, immunity and disease has, until recently, been remarkably neglected by mainstream medicine and seldom explained properly to the general public.

Can the starkly contrasting views of the uncritical Cavaliers and the sceptical Roundheads be reconciled? What are we to think when faced with conflicting claims about the mind’s role in disease?

As we shall see, the scientific truth is subtler than either of these two extreme views. It is also far richer and more exciting. It turns out that the folklore was in certain respects right, while the sceptics were wrong in their sniffily dismissive attitude. Research has uncovered an array of solid, compelling evidence that the mind does indeed play a part in a multitude of disease processes, ranging from commonplace bacterial and viral infections to heart disease and even cancer.

Some completely fictitious case histories

Before delving into the science, let us turn our attention temporarily to storytelling. If it is true that our mental state influences our physical health then this fundamental aspect of human nature ought to have been noticed and reflected in literature throughout the ages. What can we see in the mirror that fiction holds up to the human condition?

The links between the mind, emotions, behaviour, disease and death have indeed been reflected in the lives of fictional characters over the centuries. The writers describing these mind – body phenomena obviously had no conception of their biological basis, but that did not stop them noticing and portraying the connections. Throughout this book I shall be referring to literary illustrations of the links between psychological factors and disease. But first, let me spell out what these fictional case histories are intended to convey and, perhaps more importantly, what they are not intended to convey.

I shall use literary allusions because they help to convey complex scientific ideas in a recognizable form. Well-turned examples drawn from literature are more cogent and more entertaining than any medical case history, no matter how supposedly authentic it may be. They also demonstrate the antiquity and universality of many of the concepts that underlie current theories. However, by citing fictional characters or situations to illustrate scientific theories I am certainly not implying that they constitute hard evidence in support of those theories. Fine words drawn from the imaginations of long-dead authors are clearly not the same as scientific data.

The idea that physical decline can stem directly from mental and emotional decline is a familiar theme in literature. Fictional characters often die from unrequited love, grief, shame or fury. Emily Brontë’s Wuthering Heights, for example, is positively bulging with characters whose mental states lay waste their physical health. Death and disease run riot throughout the book. Let me remind you.

Believing his childhood sweetheart Catherine has spurned him, the tempestuous Heathcliff vanishes. Catherine, who does in fact love Heathcliff, is deeply upset and ridden with guilt. She consequently becomes mentally unstable and physically ill. Three years later Heathcliff returns. Catherine is torn between her love for Heathcliff and her love for Edgar Linton, whom she has meanwhile married. She breaks down under the mental pressure, shuts herself in her room and sinks into delirium. The vengeful Heathcliff subjects Catherine to an emotional battering which further weakens her health and she dies giving birth, a victim of psychological torment.

The bereaved Heathcliff determines to achieve his longed-for union with Catherine through his own death. He locks himself in a darkened room and wills himself to die. Four days later a servant enters the room to find his body. Heathcliff’s mind has killed him, as surely as if he had been shot:

Kenneth was perplexed to pronounce of what disorder the master had died. I concealed the fact of his having swallowed nothing for four days, fearing it might lead to trouble, and then, I am persuaded he did not abstain on purpose; it was the consequence of his strange illness, not the cause.

Death by shame is the tragic fate awaiting Madame de Tourvel in Choderlos de Laclos’s Les Liaisons Dangereuses, that tale of sexual intrigue among the enormously rich, enormously idle and enormously depraved aristocrats of pre-Revolutionary eighteenth-century France.

The young, pious and austere Madame de Tourvel is a devoted wife. Nevertheless, she is ruthlessly seduced by a satanic libertine, the Vicomte de Valmont – a man who ‘has spent his life bringing trouble, dishonour, and scandal into innocent families’. Valmont is egged on by the Marquise de Merteuil, his equally amoral former lover. Together they plot their seductions with the cold, unemotional precision of a military campaign.

Facing stiff resistance from the virtuous Madame de Tourvel, Valmont eventually breaks down her defences by convincing her that he will die from emotional torment unless she surrenders herself to him. Unable to resist his wiles any longer, Madame de Tourvel succumbs and Valmont has his wicked way with her.

The awful truth is then revealed – Valmont has cruelly deceived Madame de Tourvel and does not love her at all. In a fit of anguish and shame she flees to a convent, locks herself away and announces that she will not leave until she is dead. Her health rapidly deteriorates:

A burning fever, violent and almost continual delirium, an unquenchable thirst … The doctors say they are as yet unable to diagnose … As long as she is so deeply affected, I have scarcely any hope. The body is not easily restored to health when the spirit is so disturbed.

The wretched Madame de Tourvel dies, destroyed by her grief and shame. No physical agent, other than Valmont, has intervened.

Fate, however, wreaks its just revenge on the perfidious Vicomte de Valmont and Madame de Merteuil. Valmont is fatally injured in a duel. Soon afterwards, the correspondence of Valmont and Merteuil, detailing their devilish seductions, is revealed and becomes the topic of widespread gossip. Madame de Merteuil is publicly humiliated, and one day later is afflicted by a virulent attack of smallpox which leaves her horribly disfigured and blind in one eye.

Another victim of physical decline brought on by seduction and shame is the eponymous heroine of Samuel Richardson’s eighteenth-century blockbuster Clarissa. (At over a million words, it is also the longest novel in the English language.) Clarissa, a young lady of refined sensibilities, is seduced and raped by a superficially charming but unscrupulous bounder. Naturally – for this is eighteenth-century England – the dishonoured Clarissa is rejected and ostracized by her family and society. As her mental state declines, so does her physical health. Clarissa retreats into solitude and dies from grief and shame. Once again, a character’s psychological and emotional state has been the prime cause of her death.

There are of course innumerable other examples, all making similar points about the impact of emotions on health.³ We shall encounter a number of these in later chapters, and I hope it will be apparent that the notions they portray do bear some relationship to the reality revealed by modern science. However, at the risk of repeating myself, let me repeat myself: the fantasies of novelists are not the same as hard scientific evidence. Fortunately, there is plenty of that as well.

Invisible worms

O Rose, thou art sick.

The invisible worm

That flies in the night

In the howling storm,

Has found out thy bed

Of crimson joy,

And his dark secret love

Does thy life destroy.

William Blake, ‘The Sick Rose’,

Songs of Experience (1794)

The sharp divide between those who proffer psychological explanations for diseases and those who reject such theories in favour of purely physical causes is reflected in attitudes towards two particular disorders: tuberculosis and chronic fatigue syndrome.

Sir Peter Medawar, the Nobel Prize-winning immunologist and virtuoso science writer, once described tuberculosis as ‘an affliction in which a psychosomatic element is admitted even by those who contemptuously dismiss it in the context of any other ailment.’ There is abundant evidence, dating back hundreds of years, that the course and progression of tuberculosis are influenced by the sufferer’s mental state. The physical health of tuberculosis sufferers shows a tendency to deteriorate when they are subjected to severe stress or emotional upsets.

Someone who is infected with Mycobacterium tuberculosis, the bacterium that causes tuberculosis, develops a protective immune response which can hold the bacteria in check and prevent them from multiplying. The resulting stalemate between body and bacteria can mean that the disease will remain dormant for years. But if something happens to compromise or weaken the body’s immune defences, the bacteria can run riot and cause a resurgence of disease.

The importance of psychological factors in tuberculosis was widely acknowledged until well into this century. As early as 1500 BC, Hindu scripts described a wasting disease – almost certainly tuberculosis – of which one of the main causes was said to be sadness. Hippocrates, Galen and other medical luminaries of ancient Greece taught that grief, anger and other strong emotions played a major role in tuberculosis.

Throughout the seventeenth, eighteenth and nineteenth centuries many eminent European physicians stated that the causes of tuberculosis (or phthisis, as it was then known) included mental states such as ‘a long and grievous passion of the mind’, ‘a mournful disposition of the soul’, ‘ungratified desires’, ‘profound melancholy passions’ or ‘disappointment in love’. During the eighteenth and nineteenth centuries, students of tuberculosis refined the theory of a link between the disease and a specific set of psychological characteristics. This was formalized in the concept of the tuberculosis-prone personality, or spes phthisica. As we shall see later, modern science has revived the concept of disease-prone personality types with the discovery of certain intriguing associations between personality traits, heart disease and cancer.

More familiarly, we have the romantic nineteenth-century notion that consumption (as tuberculosis was then known) is caused – or, more accurately, exacerbated – by an artistic temperament. Consumptive artists or writers were believed to be consumptive primarily because of their excessive artistic and aesthetic emotions, which literally consumed them. Consumption came to be something of a status symbol among the chattering classes.

Countless noted writers, artists and musicians of the nineteenth and early twentieth centuries did indeed suffer from consumption. Emily Brontë is but one example. She died of tuberculosis, a bitterly disappointed woman, within a year of Wuthering Heights being published to withering reviews. Other creative victims of tuberculosis included John Keats, Frédéric Chopin, Robert Louis Stevenson, Stephen Crane, Katherine Mansfield, Robert Tressell, D. H. Lawrence, George Orwell and Franz Kafka. It is said that Kafka’s health was weakened by his chronic unhappiness, his hypersensitive personality, his problematic relationship with his father and several unfortunate romantic tangles. He died in an Austrian sanatorium in 1924, aged forty-one.

On the other hand, tuberculosis accounted for more than one in five of all deaths in the nineteenth century and was still common in Europe until well into this century. On statistical grounds it is hardly surprising that at least some prominent names were included among its victims.

The fiction of the eighteenth and nineteenth centuries reflects this preoccupation with tuberculosis and the prevailing attitudes towards it. We can choose from a panoply of heroes and heroines who sink into tubercular decline in the aftermath of romantic tragedy. We have, for example, the ever popular tale of La Dame aux Camélias, Alexandre Dumas the younger’s tear-jerker about the passionate but doomed love affair between Armand Duval and the enchanting courtesan Marguerite Gautier.

The young Duval meets Marguerite and is captivated by her. They become lovers. Marguerite is already consumptive, but under the healing influence of Armand’s love she abandons her dissolute lifestyle and her health improves. Meanwhile, Armand’s well-meaning father secretly persuades Marguerite that if she truly loves Armand she will leave him for his own good. Marguerite demonstrates her love for Armand by doing just that.

The cynical Armand thinks Marguerite has abandoned him out of boredom so that she can resume her former life of late nights, promiscuity and wild self-indulgence. He therefore sets out to punish her by humiliating her at every opportunity and revelling in the spectacle of her suffering:

… for the last three weeks or so, I had not missed an opportunity to hurt Marguerite. It was making her ill … Marguerite had sent to ask for mercy, informing me that she no longer had either the emotional nor physical strength to endure what I was doing to her.

As a consequence of her deep unhappiness at their separation and the psychological battering she receives from Armand, the much-wronged Marguerite goes into terminal decline. Her consumption flares up and she expires. Armand realizes his error, but not until too late.⁴ As the narrator sagely concludes: ‘I have learned that one such woman, once in her life, experienced deep love, that she suffered for it and that she died of it.’ Though Marguerite dies from tuberculosis, it is her emotions that have killed her. La Dame aux Camélias was, incidentally, modelled on Dumas’ personal experience following his affair with the courtesan Marie Duplessis. Like the fictional Marguerite, Marie died of consumption not long after the affair ended.⁵

Until the early part of the twentieth century, popular medical literature was largely in tune with fiction in the way it emphasized the importance of psychological and emotional factors in tuberculosis. To quote one everyman’s guide to medicine from the 1930s:

Happiness is a mighty important factor in the treatment of tuberculosis … Mental brooding and loss of hope of recovery or of checking tuberculosis tends to drag the unfortunate individual into a deep chasm from which escape is rare.

So, what happened and why have attitudes changed?

What happened was that in 1882 the German scientist Robert Koch announced to the world that he had discovered the real cause of tuberculosis – the tubercle bacillus, Mycobacterium tuberculosis. Once it became known that tuberculosis was a bacterial infection, scientific interest in the role of psychological and emotional factors rapidly dwindled. The pendulum swung violently from the psychological to the physical. Open a contemporary medical text on tuberculosis and the chances are you will find little mention of psychology, emotions or the mind.

A lot of the old ideas about tuberculosis were plain wrong in their assumption that mental forces were sufficient to produce the symptoms by themselves; tuberculosis is undoubtedly a bacterial infection. Moreover, identifying a specific physical cause was immensely beneficial because it enabled medical science to find an effective remedy. Improvements in social conditions in the early twentieth century, followed by the introduction of effective antibiotics after the Second World War, led to an enormous decline in the incidence of tuberculosis in industrialized nations.

And yet it remains true that psychological and emotional factors do play a role in the disease. Later in this book we shall see how. It is not the nature of the tuberculosis that has changed, but the attitudes and interests of medical science.

CHRONIC FATIGUE SYNDROME

The misleading distinction between illnesses that are ‘physical’ (in other words, real) and illnesses that are ‘psychological’ (and therefore by implication not real) is starkly illuminated by the furore over chronic fatigue syndrome, otherwise known as myalgic encephalomyelitis (ME), post-viral fatigue syndrome or, if you read the tabloid press, yuppie ’flu.

It is with some trepidation that I thrust my head into the lion’s den of controversy over the causes of chronic fatigue syndrome. Fierce arguments continue to rage and the medical establishment has yet to reach any consensus. In excess of eight hundred scientific publications have been devoted to the subject and the picture changes almost weekly. Those who suffer from the illness often have passionate views about its origins and anyone who gainsays them is asking for trouble.

The debate about chronic fatigue syndrome is relevant here because it exemplifies the false dichotomy between ‘psychological’ and ‘physical’ origins of illness. Throughout the controversy runs a seductively misleading vein: the implicit assumption that the illness must be either physical or psychological in origin. But first, what exactly is chronic fatigue syndrome?

Since 1988 the term chronic fatigue syndrome (CFS) has been used to describe a debilitating illness of unknown origin that has persisted for at least six months. As you probably know (for it is often in the news) CFS is characterized by a dreadful, disabling tiredness that is made worse by any physical exertion. This fatigue is accompanied by a motley assortment of other symptoms, including general malaise, intermittent fevers, pains in the joints, stiffness, night sweats, sore throats, poor co-ordination, visual problems, skin lesions and sleep disorders.

As if that were not enough, many CFS sufferers also experience psychological problems such as severe depression, forgetfulness, poor attention and lack of concentration. CFS can persist for years and it ruins the lives of those afflicted. Often they will be forced to give up work. Sufferers may show a measure of improvement over time, but the majority remain unwell for several years.

Cases of CFS have been reported in most industrialized nations including Britain, the USA, Canada, France, Spain, Israel and Australia. Sufferers tend to be young adults between twenty and fifty, though children can also be affected. According to the American Centers For Disease Control and Prevention, more than 80 per cent of CFS sufferers are women, most are white and their average age when the illness develops is thirty. Another common factor is that sufferers usually report having contracted some form of viral infection not long before the syndrome manifested itself.

As yet, no one has come up with a truly effective remedy for CFS. None of the drugs that have been used to treat the syndrome is of proven effectiveness and some may do more harm than good.

CFS, as currently defined, is a relatively recent phenomenon. (But then, so is AIDS; the fact that a disorder has only recently been recognized and defined does not detract from its reality.) Records of vaguely CFS-like syndromes, involving severe fatigue, muscle pains and other symptoms, date back at least two centuries. The medical history books, however, contain nothing that can be unequivocally compared with CFS before the second half of the nineteenth century, when neurasthenia became a common diagnosis. Incidentally, cultural stereotypes about the sort of person who was susceptible to neurasthenia were as strong in the nineteenth century as they are now about CFS. Neurasthenia was said to be a disease of affluent middle-class women, in much the same way that CFS has been inaccurately portrayed by the popular media as ‘yuppie ’flu’, a disease of affluent thirtysomething professionals.

It was not until the first half of the twentieth century that reports of a disorder corresponding to CFS started to accumulate. The first well-documented outbreak of a CFS-like disorder occurred in the 1930s in the USA and was attributed to a mystery virus. A similar mystery ailment afflicted the staff of a London hospital in 1955, in what became known as the Royal Free epidemic. The sufferers experienced persistent muscle pain and fatigue. To begin with the syndrome was referred to as benign myalgic encephalomyelitis. By 1956, however, it had proved to be anything but benign, and so it became known simply as myalgic encephalomyelitis, or ME.

Since they first appeared on the medical map, CFS-like illnesses have gone by a baffling variety of names including epidemic neuromyasthenia, neurasthenia, Iceland disease, Royal Free disease, atypical poliomyelitis, fibrositis, fibromyalgia, post-infectious neuromyasthenia, post-viral fatigue syndrome and myalgic encephalomyelitis. It is not certain that all these illnesses have been identical with what is now referred to as chronic fatigue syndrome. An analysis of twelve well-documented outbreaks of CFS-like disorders found they differed in various respects, notably with regard to neurological problems.

Now we come to the real meat of the problem. No one yet knows for certain what causes CFS. The arguments continue to rage and there are major divisions of opinion within the medical community. But what characterizes the whole debate – especially as it is portrayed in the popular media – is the implicit distinction between physical causes, which are held to be genuine, and psychological causes, which are held to be suspect.

With a few honourable exceptions, expert opinion on CFS divides neatly into two opposing camps. In one camp are those who maintain that CFS has a physical cause such as a virus or an immunological disorder. According to this view, the depression and other psychological symptoms that characterize CFS are consequences rather than causes of the underlying physical disorder.

In the opposing camp are those who argue instead that CFS is fundamentally a psychological disorder. According to this view, the physical symptoms such as exhaustion, muscle pains, fever and malaise, are manifestations of an underlying psychiatric problem.

Which view is correct? You may not be surprised to find that both are at least partially true. Many CFS sufferers have symptoms that match the diagnostic criteria for psychiatric disorders and organic disease. The evidence is undoubtedly complex and equivocal but it points towards one conclusion: that chronic fatigue syndrome has both physical and psychological components. Let us examine some of this evidence.

Most cases of CFS are preceded by a viral infection of one kind or another, and there have been repeated suggestions that a virus might lie at the root of the syndrome. For a long time the prime candidate was the Epstein-Barr virus, a member of the herpes virus family which is also responsible for glandular fever. During the 1980s chronic fatigue syndrome was widely referred to as ‘chronic Epstein-Barr virus infection’, as though its viral origins had been firmly established. Other candidates have included retroviruses (of which HIV is an example) and polio-like viruses called enteroviruses.

There is as yet no conclusive evidence to support the viral theory and it has therefore fallen out of favour. But even if viruses are not the prime cause of CFS, it remains highly plausible that a viral infection might help to trigger or precipitate the syndrome when other causal factors are also present.

Several other physical causes besides viruses have been proposed. One theory maintains that the primary symptoms of CFS are produced by hyperventilation – that is, abnormally rapid breathing. The evidence, however, is once again scant. Only a minority of CFS sufferers hyperventilate. On another tack, research at Johns Hopkins University in Baltimore has indicated that certain types of chronic fatigue (though not necessarily all cases of CFS) might result from abnormally low blood pressure. Yet another suggestion has been that CFS stems from a form of neurobiological disorder. One study revealed that more than a quarter of CFS patients had abnormal brain scans, and subtle changes have been found in the levels of neurotransmitter substances in the brain.

At present, the most favoured physical theories about the origins of CFS revolve around the immune system. There is growing support for the view that the symptoms of CFS result from a perturbation or abnormality in the sufferer’s immune system. This immunological malfunction, it is argued, may be triggered by a viral infection which somehow throws the immune system out of kilter.

Evidence that CFS involves an immunological disorder is accumulating rapidly. Within the past few years various abnormalities have been found in the immune systems of CFS sufferers. These include alterations in the activity and surface structure of two important types of white blood cells: the natural killer cells and T-lymphocytes. (You will be hearing much more about these cells in later chapters.) It is becoming increasingly evident that CFS is associated with, if not directly caused by, a persistent, low-level activation of the immune system.

If CFS really is an immunological disorder then why do some perfectly sensible scientists and physicians persist in regarding it as primarily a psychological disorder? They persist because there is highly respectable evidence to support their viewpoint as well.

Several of the symptoms associated with CFS are also seen in psychiatric illnesses, notably depressive and anxiety disorders. A substantial proportion of those who seek medical help for chronic fatigue turn out to have a recognizable psychological problem. The authoritative Centers For Disease Control and Prevention in the USA has concluded that approximately 45 per cent of all CFS sufferers have some form of identifiable psychiatric disorder before the onset of CFS. Researchers at the University of Connecticut School of Medicine found that as many as three out of four of the chronic fatigue cases they examined could be more easily explained by psychiatric problems such as depression. To add to the picture that the mind plays a central role in the illness, Australian researchers have discovered that CFS patients exhibit significantly more signs of hypochondria than other medical patients.

Psychological theories of CFS have tended to focus on depression. Over half of all CFS sufferers exhibit clear signs of clinical depression. Often the depression appears to have preceded the chronic fatigue, suggesting that it might be a cause rather than a consequence of the syndrome. Severe depression is usually accompanied by prolonged reductions in physical activity which could, in turn, lead to a debilitating decline in muscle function. People who lie in bed for long periods become physically weak. The sleep disturbances that typify some depressive disorders might also exacerbate the sufferer’s fatigue. Furthermore, it is known that severe depressive disorders are associated with changes in the immune system.

But hold fast. It is equally clear that many CFS sufferers become depressed as a consequence of their illness. It is hardly surprising that those suffering from a debilitating but unexplained illness should become depressed and abnormally preoccupied with their health. Although more women than men suffer from CFS this should not be interpreted as evidence that CFS is primarily a psychological disorder, as a few sexist pundits have implied. There are several perfectly respectable organic diseases, such as rheumatoid arthritis, which show a marked preference for one sex over the other.

At present it is probably safe to conclude that the case for CFS being primarily a psychological disorder remains unproven. The evidence for some sort of immunological malfunction is too good to dismiss. There is, however, no doubt that CFS sufferers’ psychological reactions to their illness do have an important bearing on their wellbeing and recovery. Whether depression is a cause or an effect of the syndrome, it becomes a major problem in its own right and can seriously impede recovery.

The controversy over CFS is further complicated by the attitudes of those who suffer from it. People who are afflicted by a serious and debilitating disorder such as CFS want their illness to be publicly recognized as having a medically respectable cause. For most people this means a physical cause, such as a virus or an immunological disorder, rather than a psychological cause. Any suggestion that their symptoms might result from a psychiatric problem tends to provoke outrage.

This attitude is understandable. Talk of psychological causes often carries with it an unjustifiable connotation that the illness is not quite genuine. There is usually a strong whiff of ‘get a grip on yourself and snap out of it’ in the air. Moreover, even in the late twentieth century there is still a wholly unreasonable stigma attached to mental illness. The average person would rather admit to having a physical illness, albeit a vague ‘mystery’ virus or obscure immunological malfunction, for this absolves them of any accusations of malingering, neuroticism or weakness of character. One unfortunate outcome of this desire for a physical explanation is the tendency, in some countries at least, for CFS sufferers to shop around until they find a physician who will give them the diagnosis they want.

Ironically, it turns out that the CFS sufferers who believe most strongly in a purely physical explanation have greater difficulty in recovering from their illness. This may be because they fail to confront and deal with the psychological problems that invariably accompany the illness.

Evidence to support this conclusion has come from a study conducted by Michael Sharpe and colleagues in Oxford. They found that a form of cognitive behavioural therapy, in which CFS sufferers were helped to re-evaluate their attitudes towards their illness, was of major benefit. More than 70 per cent of CFS sufferers who received the behavioural therapy regained their ability to function normally, compared with a success rate of 27 per cent for sufferers who received only standard medical care.

The pressure to attribute CFS to purely physical causes has also had a substantial influence on how the popular media deal with the subject. Newspaper and magazine articles, TV features and self-help books tend to emphasize physical explanations for CFS and neglect its psychological aspects.

A survey by researchers at the University of London found that 69 per cent of all articles on CFS which had appeared in national newspapers and women’s magazines since 1980 had favoured physical causes, compared to a mere 31 per cent of research papers in scientific and medical journals. There appeared to be a systematic bias in the popular media towards reporting physical as opposed to psychological explanations. Even the choice of name was affected. Whereas scientific papers typically used the neutral term chronic fatigue syndrome, the popular media instead favoured the more medical-sounding myalgic encephalomyelitis (ME).

Similar attitudes apply to other illnesses which, like CFS, have been tarred with the psychosomatic brush. Asthma and allergies are familiar examples. So too are inflammatory bowel disorders such as Crohn’s disease and ulcerative colitis. The pendulum of opinion has swung violently back and forth over the years. Half a century ago asthma was widely regarded as an essentially psychological illness. Nowadays it is normal to play down the role of psychological and emotional factors and instead focus almost exclusively on its immunological mechanisms and physical triggers, ranging from fitted carpets to car exhaust fumes. In truth, there are good grounds for believing that both immunological and psychological factors play important roles in these diseases. Nevertheless, the overwhelming tendency is to opt for one explanation to the exclusion of the other.

As we shall see in subsequent chapters, this centuries-old opposition between mind and body, mental and physical, psychosomatic and organic, is a snare and a delusion. It has impeded scientific understanding and acceptance of some very important phenomena. There is nothing ‘alternative’ or scientifically dubious about the fact that what goes on inside someone’s brain influences their physical health.

2 Shadows on the Sun

Had she been light, like you,

Of such a merry, nimble, stirring spirit,

She might ha’ been a grandam ere she died;

And so may you; for a light heart lives long.

William Shakespeare, Love’s Labour’s Lost (1595)

In Tobias Smollett’s epistolary novel The Expedition of Humphry Clinker (1771), Mr Matthew Bramble makes this perceptive observation in a letter to Dr Lewis:

I find my spirits and my health affect each other reciprocally – that is to say, every thing that discomposes my mind produces a correspondent disorder in my body; and my bodily complaints are remarkably mitigated by those considerations that dissipate the clouds of mental chagrin.

Is the centuries-old notion that the mind plays a pivotal role in physical disease an established fact or unsubstantiated folklore? In this chapter we shall consider some of the many strands of scientific evidence for and against that notion. Precisely how the mind affects physical health is a question we shall leave until later. But first we must clear a conceptual hurdle out of the way.

The perfectly sensible idea that the mind can influence our susceptibility to disease is often muddled with the different, but equally venerable, notion that the mind can by itself conjure up phantom illnesses which have no physical basis. We are about to encounter the psychosomatic fallacy.

According to one fairly representative modern definition psychosomatic illness is ‘any illness in which physical symptoms, produced by the action of the unconscious mind, are defined by the individual as evidence of organic disease and for which medical help is sought’ [my italics]. By this definition, the unfortunate victim might feel ill even though he or she has no underlying physical disease. In other words, mental state is the sole and sufficient cause of the physical symptoms. Such things do, of course, happen; we shall take a look at them in chapter 3. But they are not a major concern of this book. In fact, they are something of a distraction.

Psychological and emotional factors can determine whether or not someone becomes ill but they mostly do this by altering that person’s susceptibility to disease. They are rarely the sole and sufficient cause of illness. A less misleading definition of ‘psychosomatic’ is one in which psychological factors play a contributing role in the development of the illness, alongside other factors such as bacteria, high blood pressure or smoking. But by this definition most illnesses in the Western world today can be termed psychosomatic.

The misleading conception of illnesses as mere phantoms, conjured up by the unconscious mind, has its roots in the psychoanalytic theories of Sigmund Freud. According to Freud and his disciples many mental and physical disorders have their roots in emotional conflicts, of which the patient may have no conscious awareness. These unconscious emotional conflicts are translated into physical symptoms such as pain, paralysis or loss of sensation. The symptoms are regarded by the sufferer – though not necessarily the rest of the world – as legitimate signs of a genuine organic illness. This dubious concept of psychosomatic illness lives on and can still be found lurking within the pages of popular health and self-help books.

Freudian psychoanalytic theories laid the foundations for what later became known as psychosomatic medicine, a field which came into being during the 1930s and 1940s. The earliest practitioners of psychosomatic medicine sought explanations for mysterious disorders such as asthma, allergies, arthritis, high blood pressure and peptic ulcers in underlying emotional conflicts and personality characteristics. Psychosomatic theories about asthma, for example, revolved around such notions as the fear of losing parental love. As a natural consequence of their Freudian leanings, many of the early psychosomatic practitioners tried to treat disorders like asthma and allergies using psychotherapy – with fairly mixed results.

We, on the other hand, shall be moving firmly within the realm of ‘real’ diseases like the common cold, herpes, coronary heart disease and cancer, rather than those shadowy and mysterious maladies to which the epithet psychosomatic is usually applied. The diseases we shall be focusing on in subsequent chapters are caused by real bacteria, real viruses, real clogged arteries or real cancer cells. They are most certainly not just ‘all in the mind’.

Death, disaster and voodoo

Sometimes – quite often, in fact – people drop dead with little or no warning because something goes wrong with their heart. This phenomenon is called sudden cardiac death. It is normally defined as an unexpected heart failure within twenty-four hours of the first symptoms (if any) being noticed.

Sudden cardiac death accounts for about 15 per cent of all mortality from natural causes. Though victims may have no previous medical history of heart problems, autopsy generally reveals a pre-existing but hitherto undiscovered disease. Unfortunately, in more than half of all cases the first manifestation of this disease is death.

For centuries people have believed that severe psychological stress, grief, fear, anger or other strong emotions can trigger sudden cardiac death. There is massive anecdotal evidence that distressing events such as the death of a loved one, the loss of a job or even a heated argument can trigger a fatal heart attack. In recent years scientists have accrued a satisfyingly solid mountain of systematic evidence to confirm the anecdotes.

When scientists analyse the immediate precursors of sudden cardiac death they consistently find that a large proportion of its victims have experienced unusually high levels of emotional distress in the hours or days leading up to death. One study, for example, found that 40 per cent of men who died unexpectedly from heart failure had experienced a significant emotional upset, such as being involved in a car accident or receiving notification of divorce proceedings, within the twenty-four hours immediately preceding their death. There have even been documented medical reports of individuals dying after being severely disturbed by upsetting thoughts or recollections of a traumatic experience.

One of the most common precursors of sudden cardiac death is the extreme fatigue and exhaustion known as burnout. Like consumption in the nineteenth century, burnout has become something of a bizarre status symbol. Burnout is seen as the ‘red badge of courage’ in professional circles, proof of Herculean labours and overwhelming workloads. (This says a great deal about present cultural values. In the nineteenth century consumption lent status because it supposedly denoted creativity and artistic passion; nowadays it is the sloggers we prize.)

Whatever the cultural overtones, there is a significantly higher risk of sudden cardiac death for victims of burnout. Those who exhibit the classic symptoms of intrusive anxiety, irritability and mental exhaustion may feel that way because of a mechanical fault in their heart. In many cases, however, burnout is more a symptom of prolonged psychological stress. In combination with a pre-existing weakness in the heart or coronary arteries it can easily be lethal. Dutch research which tracked the health of a large sample of middle-aged men over several years found that individuals who reported feeling mentally and physically exhausted at the end of the day were more than twice as likely to die from a heart attack. This was true even for men who had hitherto been free from any coronary heart disease.

In chapter 8 we shall be looking in greater depth at the biological mechanisms whereby the mind can damage the heart and coronary arteries. Suffice it here to say that there are plenty of well-understood biological mechanisms which enable stress-induced changes in the brain to trigger sudden cardiac death, especially where coronary heart disease is already present.

Sudden death can also be provoked by traumatic events on an impersonal scale. We have already considered the case of the Israeli citizens who died during the Gulf War from psychological stress generated by Iraqi missile attacks. Nature has conducted some of its own experiments in stress-induced death. Take earthquakes, for example. An analysis of mortality statistics immediately after a major earthquake will usually reveal a transient rise in the number of deaths from heart failure and other natural causes, unconnected with the direct physical effects of the earthquake. For instance, in 1978 the Greek city of Thessaloniki was hit by two earthquakes. Official records showed a marked increase in deaths from natural causes, especially heart failure. During the three-day period spanning the earthquakes and their immediate aftermath, the rate at which the local population were dying from heart disease shot up by 200 per cent and the death rate from other natural causes increased by 60 per cent.

Similarly, when Australian scientists investigated the aftermath of an earthquake which struck New South Wales in 1989 they found that the incidence of fatal heart attacks in the locality went up by 70 per cent. In these and other cases it was clear that psychological stress had brought about the premature deaths of vulnerable individuals.

Then we have those strange tales of voodoo, or ‘hex’, death. The unfortunate victim is ritually cursed by a witch doctor, voodoo priest, bokor or other symbolic authority figure. Once the death sentence has been pronounced the victim duly obliges by giving up the ghost and dying, usually within a few days. Competent and trustworthy authorities have been documenting instances of voodoo death since at least the sixteenth century, in places as far apart as Africa, South America, the Caribbean and Australia. It cannot be dismissed as the product of lurid fantasies.

The religious and cultural details vary, but reliable reports of voodoo death share certain basic features. First and foremost, the victim must be highly suggestible, with an unquestioning belief in the power of the sorcerer or witch doctor who curses him. He must also be totally convinced that he is powerless to do anything to save himself. An attitude of helplessness is essential: once the bone has been pointed or the curse uttered, the victim loses any will to live. Sceptics, scientists and tourists do not die from voodoo curses. A third important ingredient is social pressure. It speeds things along no end if everyone else in the victim’s social world shares the same beliefs. Family and friends reinforce the victim’s belief in the inevitability of death, abandoning the unfortunate individual to die in complete isolation.¹ The enormous importance of social relationships for mental and physical health is a theme we shall return to later.

Literature is replete with characters who drop dead from the effects of overpowering emotion. Shakespeare’s King Lear, for example, dies of a broken heart when his favourite daughter Cordelia is cruelly murdered shortly after Lear is reconciled with her. On discovering Cordelia’s body, Lear gives vent to his crushing grief:

Howl, howl, howl, howl! O, you are men of stones!

Had I your tongues and eyes, I’d use them so

That heaven’s vault should crack. She’s gone for ever.

Then Lear drops down dead.

Trouble, strife and sickness

Intense emotion usually falls short of causing people to drop down dead; it may simply make them more vulnerable to illness. And here again, at least some of the folklore has withstood scientific scrutiny. Research has confirmed the existence of systematic links between psychological factors such as anxiety, stress, depression and hostility, and a wide range of physical disorders including minor infections, gut disorders, herpes, allergies, asthma, arthritis, coronary heart disease and cancer. Indeed, according to some characteristically controversial research by the London University psychologist Hans Eysenck, certain psychological measures of personality and behavioural style have a greater bearing on which individuals will die from cancer or heart disease over the following ten to fifteen years than whether or not they are smokers.

Anxiety and stress have frequently been linked with vulnerability to illness. Numerous long-term studies have found that people who experience pronounced feelings of tension or anxiety are substantially more likely to develop coronary artery disease, or die from it, over the following years. For example, an American study which tracked several hundred people over a twelve-year period found that individuals who exhibited high levels of psychological distress were roughly twice as likely to die as those with only average levels of distress. This connection between distress and death held up even when other medical risk factors such as old age, obesity, smoking, high blood cholesterol and high blood pressure were taken into account, so it was not merely a question of distressed subjects also being old, fat or smokers. Psychological distress was related to subsequent mortality in its own right.

Similar conclusions emerged from a Harvard University project. This investigated the health of former Harvard students whose psychological and biological profiles had been assessed thirty-five years earlier, as part of a series of laboratory experiments on stress. The way subjects reacted during the laboratory tests predicted their physical health years later. Individuals who displayed signs of severe anxiety during the original stress tests subsequently suffered from significantly more physical illnesses, including coronary heart disease, over the following decades. Responding anxiously to a stressful situation when a young adult proved to be a reliable marker for ill-health of all types in middle age. Another investigation by scientists at Harvard Medical School found that very shy children, who suffered from severe anxiety when in social situations, were more prone to allergic disorders such as hay fever.

It may help to look in greater detail at one specific example of a fairly subtle connection between psychological factors and subsequent disease. An American research project conducted in the 1970s investigated the psychological characteristics associated with infectious mononucleosis, otherwise known as glandular fever. This unpleasant and debilitating disease is prevalent among teenagers and young adults. The symptoms include a general malaise, fever, sore throat, loss of appetite, headaches, together with swelling of the lymph nodes or ‘glands’ in the neck, groin and armpits. Recovery can take many weeks. Occasionally, serious complications arise, such as damage to the liver or spleen.

The disease is caused by a type of herpes virus known as the Epstein-Barr virus (EBV), which we encountered in chapter 1 as a once-favoured cause for chronic fatigue syndrome. In common with other herpes viruses like herpes simplex (which causes cold sores and genital herpes), EBV can remain dormant in the body for years without causing any symptoms. Dormant viruses are normally held in check by the individual’s immune system, but anything that weakens immunological control over the latent viruses can trigger the emergence of disease symptoms.

The subjects of this investigation comprised over 1300 young men entering the West Point military academy. On arrival at West Point each student was screened to see whether he was already infected with EBV. About two-thirds of the students carried the virus, which is typical for a normal population. The remaining third had not yet been infected. These potentially susceptible students were then tracked to see who would become infected with EBV. And here lies an important general point: not everyone who is exposed to disease-causing bacteria or viruses becomes infected. In fact, only about one in five of the originally virus-free students went on to be infected with EBV during their four years at West Point. Of those who did become infected, a quarter developed obvious clinical symptoms of disease. And here lies a second general point: not everyone who gets infected with disease-causing viruses or bacteria develops a clinical disease.

Psychological assessments revealed that those men who went on to be afflicted with infectious mononucleosis shared certain distinctive psychological characteristics. In particular, they tended to be the ones who had suffered most from academic pressure. Students who had the dispiriting combination of a strong motivation to do well, but a poor actual performance, had a greater likelihood of contracting infectious mononucleosis. And once they became ill these highly motivated but poorly performing students spent longer on average in hospital. They were more susceptible to the disease and when they got it, they got it worse.

Relatively minor traumatic events can also push up the odds of becoming ill. For example, Australian scientists found a marked increase in high blood pressure, gut disorders and diabetes among people who had been indirectly affected by a bushfire that occurred in southern Australia in 1983.

Long-term observations of normal families have shown that there is often an increase in family-related stress, or disruptive changes in family circumstances, in the period immediately before one or more family members develop infections. A number of studies of families in their home environments have unearthed associations between stressful conflicts and minor infectious illnesses such as coughs, colds, ’flu and sore throats. These stressful episodes tend to precede infections rather than follow them, implying that the stress contributes to the illness and not vice versa. In other words, it is not simply a matter of arguments arising because everyone is feeling ill and crotchety.

Research in the States has uncovered comparable links between stress and illness among children in rural Dominica. In the week following a high-stress event such as a big family upheaval, the risk of the children acquiring an infection of the upper respiratory tract increased by a factor of three.

Life events

For over thirty years scientists have been systematically exploring the idea that the risk of falling ill increases when we are exposed to a lot of disruptive changes or emotional turmoil. This research stemmed from the informal observations of certain perceptive doctors, who noticed that their patients often seemed to have experienced unusually large amounts of change and upset in the period before they fell ill. Further impetus came from a pioneering investigation of illness and absenteeism among the employees of the Bell Telephone Corporation in the 1950s. This indicated that employees with unsettled personal lives tended to suffer frequent bouts of illness and take more sick leave from work.

Suggestive observations such as these led psychologists to formulate the concept of life events. A life event is defined as any significant change in a person’s circumstances which requires them to make psychological and practical readjustments. The disruptive event can be either desirable or undesirable; the prime criterion is that it causes a degree of upheaval.

Examples of life events include the death of a partner or family member, divorce, marriage, starting a new job, moving house or financial problems. At the other end of the scale, minor upheavals such as family holidays and Christmas are also classified as life events. The basic hypothesis underlying this work is that any disruptive changes, whether desirable or undesirable, are potentially stressful and can increase our chances of falling ill.

Thousands of research projects have investigated the relationships between life events and health. The majority of these studies have used a standardized method for assessing life-event stress called the Social Readjustment Rating Scale. In its simplest form this involves asking each individual to record which of forty-three types of life event they have experienced over a specified period, usually between six months and two years.

Each type of life event is assigned a standard score according to its supposed severity, rated on a scale from o (least severe) to 100 (most severe). The maximum rating of 100 is awarded to the death of a spouse; divorce is rated 73; marriage, 50; changing to a different line of work, 36; moving house, 20; Christmas, 12; and so on. (Personally, I would rate Christmas at around 60, and anyone who has recently experienced the horrors of moving house may be excused for wondering at its modest rating.) A composite score is then calculated for each individual, taking account of both the total number of life events they have experienced and the relative awfulness of those life events. A high score can denote a few serious life events or a multitude of minor ones.²

If it is true that life events act as risk factors for illness then people who register high life-event scores should, on average, have more illnesses than those whose lives have been undisturbed by change. Simple. By and large, this is what the research has found.

A seminal early investigation looked at the effects of life-event stress on US Navy personnel during the Vietnam War. The results showed that individuals with the highest life-event scores suffered almost twice the number of illnesses over the following months as those with low scores. In another study scientists asked young men in a navy submarine training establishment to record the life events they had experienced over the previous twelve months; again, the incidence of life events correlated with subsequent illness.

The general conclusion from several thousand such studies is that people who have been exposed to lots of life-event stress have a slightly greater risk of illness. This increased risk applies across the board and seems to encompass virtually every form of ailment and disease under the sun, ranging from headaches, common colds, allergies and inflammation of the gums to mental illness, coronary heart disease, leukaemia, diabetes, tuberculosis and multiple sclerosis. Life-event stress also has an impact on childbirth; women who register high stress ratings during the year or so before pregnancy tend to give birth to babies with slightly lower birth weights and a slightly poorer overall state. Life events are even associated with an increased risk of minor accidents and sports injuries.

As well as suffering more episodes of illness, people with high life-event scores also tend to be ill for longer, have more severe symptoms and take longer to recover.

Not surprisingly, the adverse effects of life events are generally worse when the life events are severe, undesirable and clustered together in time. In the early days of life event research it was widely assumed that ‘good’ life events, such as getting married or starting a new job, were potentially just as damaging to health as ‘bad’ life events of comparable disruptiveness. However, more recent research has tended to support the common-sense assumption that, other things being equal, undesirable life events are inherently more damaging than desirable ones.

It has to be said that the link between life events and later illness is not as neat and simple as it sometimes appears. Some of the research on life events has been justifiably criticized for a variety of reasons. This is not the right place to debate the abstruse technicalities of research methodology. Nonetheless, the difficulties inherent in life event research are of broader relevance and therefore merit our attention.

First of all, the statistical correlation between life events and illness is highly consistent but it is also fairly weak. Life events do have a bearing on health, but not a very major bearing. Typically, life events account for only about 10–15 per cent of the total variation in the incidence of illness. A number of those who are exposed to stressful life events become ill, but most do not. Conversely, it is possible to fall ill despite living a life of unruffled stability. A phenomenon that is highly significant in a strictly statistical sense – meaning that the patterns in the data are more than just chance variations – may not necessarily be highly significant in a clinical or scientific sense.

A second fundamental point is that correlation is not the same as causation. The existence of a statistical association between two things is not proof that one of them causes the other. The population of the world and the age of the current pope are correlated, but there is no causal connection between the two. They both happen to be independently related to a third variable – time. So the correlation between life-event scores and illness does not by itself prove that life events are a direct cause of illness. The causation might even work the opposite way round; that is, chronic illness might conceivably precipitate life events. For instance, someone’s marriage or career might run into problems because they are ill. And it may be the case that things which are classified as life events, such as sexual problems or changes in sleep patterns, could in fact be symptoms of an existing but undiagnosed illness.

In order to disentangle cause and effect in this type of research it is vital to establish which came first, the life events or the illness. There is plenty of evidence that life events do indeed tend to precede illness, which suggests that they may genuinely contribute to ill health.

A third pitfall with life event research, especially in its early days, has been its retrospective nature. When investigators ask subjects to recall their life events during, say, the previous year, great reliance is placed on frail and faulty memories. And therein lies a weakness. It is an awkward fact of life that most of us grossly over-estimate our ability to recall the past accurately and objectively. Ask any policeman, lawyer or judge about the reliability of witnesses to crimes. Psychologists have found that after a period of ten months people are typically able to recall life events with an accuracy of only 25 per cent. Conclusions that depend on people’s memories of what happened to them one or two years ago are therefore bound to be suspect.

As well as the inherent difficulty of recalling past events accurately there is also a danger of systematic bias. People who are unwell may focus on a particular trauma in their past and assume it must have been responsible for their illness. We all have a basic need to find explanations for our illnesses and some people understandably attribute their poor health to traumatic experiences. But in doing so they inadvertently undermine the objectivity of the research data.

Fortunately, not all research on life events has had to rely on faulty memories. Instead, scientists have monitored groups of initially healthy subjects over a period of time, recording their life events and illnesses as and when they happen. This style of research is referred to as prospective, in contrast to the backward-looking retrospective method. And plenty of these prospective studies have borne out the link between life events and subsequent illness.

Another potential pitfall lies in failing to distinguish between an interviewee’s actual health, as measured according to objective, clinical criteria, and what they say or think about their health. The problem here is not that people deliberately lie; the majority of those who volunteer to take part in scientific research try hard to be truthful. The real problem is that few of us are capable of being entirely objective about our own health. We all perceive and interpret our physical symptoms in different ways; something that would constitute a distressing malady for one person might not even be noticed by another.

Problems also arise if we attempt to measure health in terms of what is called sickness-related behaviour. This means behaviour like going to the doctor or taking sick leave from work. Sickness-related behaviour is obviously not the same thing as actual sickness.

The way humans respond when they think they are ill depends on other factors besides their state of health, including such mundane considerations as whether expert medical advice is freely and conveniently available. Sickness-related behaviour is often more a reflection of psychological factors than physical health.

To complicate matters further, people’s perception of their own state of health varies according to their mental and emotional state. Anxious or stressed individuals, for example, are more apt to notice and worry about minor symptoms, interpret them as evidence of disease and seek expert help. Someone who has been experiencing lots of stressful life events is more likely to feel unwell and visit their doctor, but this does not necessarily mean that they are actually ill.

We shall be looking at this issue in more depth in the next chapter. Suffice it here to say that there is a world of difference between believing yourself to be ill, or going to the doctor, and having a clinically verifiable disease. For this reason, research that relies wholly on self-assessments of health or on sickness-related behaviour can be misleading. Such measures often say more about people’s mental state than they do about their true physical health. I should add, however, that the dubious practice of using sickness-related behaviour as an ersatz measure of health is a pervasive problem in medical research and is certainly not unique to work on life events.

Despite these caveats there is consistent evidence, garnered from thousands of scientific studies, for a connection between life events and subsequent illness. It is now clear that even the mundane hassles of everyday life have an impact on physical health. Indeed, some scientists have argued that because these hassles are such a frequent occurrence their cumulative influence on health may be more pervasive than the effects of rarer, but more traumatic life events.

The general idea that psychological factors can affect susceptibility to physical illness is amply supported by research on other species. As in so many other respects there is nothing biologically unique about humans. Several decades of experimental work on other species have confirmed that various forms of psychological stress can increase (or, occasionally, decrease) animals’ susceptibility to a wide spectrum of diseases, including bacterial and viral infections, heart disease and cancer.

For instance, when mice or rats are exposed to stressful situations, such as being physically restrained or subjected to unpleasant electric shocks, they become less resistant to infection with a whole range of bacteria, viruses and parasites including mycobacteria (the type of bacteria responsible for tuberculosis), herpes viruses, influenza viruses, polio viruses and the protozoa which cause toxoplasmosis. In one experiment, for example, frightening mice by exposing them to a cat significantly increased their vulnerability to infection with a parasitic tapeworm. (The cat was prevented from attacking the mice; the sight of it alone was enough to affect them.) Likewise, the social stress of being introduced into an unfamiliar flock makes chickens more susceptible to bacterial infections, while the stress of being transported renders cattle vulnerable to a form of viral pneumonia caused by the reactivation of latent herpes viruses.

The sheer volume of animal research in this field makes it impossible to describe more than a tiny and rather haphazard selection of examples. And some of the experiments, especially those performed in the dim and distant past, are too grisly and unethical to deserve a mention. We humans are not the only animals whose physical health can be damaged by upsetting events.

The mind and the common cold

The way in which psychological factors can affect our susceptibility to disease is illustrated by research on that most mundane of illnesses, the common cold.

For centuries it has been widely believed that stress makes us more prone to minor respiratory infections such as colds and ’flu. This has now been confirmed experimentally. It is surprising that until recently much of the scientific evidence regarding the effects of psychological factors on respiratory infections was suggestive rather than conclusive.

In one study, for example, researchers asked married couples to fill in a questionnaire each day for three months, recording the various stresses and hassles of everyday life together with their state of health. The results showed that respiratory infections tended to be preceded by a greater than average degree of stress. Typically, a few days before the onset of symptoms there would be a rise in the number of unpleasant life events and a drop in the number of desirable events.

Much firmer evidence came from a pioneering experiment in which psychologist Richard Totman and colleagues infected healthy volunteers with cold-inducing rhinoviruses, having first assessed each individual’s psychological profile. It transpired that personality and previous exposure to stress had a significant bearing on both the risk of infection and the severity of the subsequent cold. Individuals with introverted personalities developed more severe colds, as did those who had experienced certain types of stressful life events.

The volunteers in this experiment were deliberately infected with viruses in order to avoid a potential ambiguity that had undermined previous research. Critics had pointed out that a correlation between psychological factors and colds could be attributed to varying degrees of exposure to cold viruses, rather than anything to do with biological resistance to infection. Individuals with shy personalities, say, or those who have recently experienced a traumatic life event, might be inclined to stay at home and would therefore have fewer opportunities to catch a cold.

By exposing all subjects equally to cold viruses Totman’s experiment excluded this possibility. The fact that psychological measures still predicted the clinical outcome implied a more direct link between mental state and disease.

The technique of deliberately exposing people to bacteria or viruses in order to assess their vulnerability had, incidentally, been used before. In one hair-raising experiment in the early 1970s a group of healthy (and obviously well-motivated) volunteers were exposed to bacteria which cause a plague-like disease, with symptoms including prolonged fever, vomiting, headaches and swollen lymph nodes. Two days before they were infected each subject’s stress level was assessed using standard psychological techniques. Those who registered the highest stress levels went on to have the most severe fevers.

Further compelling evidence for a connection between psychological stress and colds came a few years ago from a similar experiment. It is worth considering this experiment in detail because it illustrates some important general points.

Sheldon Cohen and colleagues recruited 420 healthy men and women and installed these worthy volunteers in residential accommodation at the British Medical Research Council’s Common Cold Unit in Salisbury. They then used standard psychological techniques to assess the mental state and stress level of each volunteer. Specifically, the researchers noted the life events that each subject had experienced over the previous year; the extent to which subjects perceived themselves as unable to cope with the demands placed on them by life; and each individual’s current emotional state. The volunteers were then exposed to a standard dose of cold viruses which matched the level of virus exposure one might expect to find in normal life. Each subject was given nasal drops containing one of five viruses capable of producing a common cold.³

Over the following week the subjects were monitored to see if they had been infected and, if so, whether they then developed clinical symptoms of a cold. Each day a doctor examined them for signs and symptoms of a cold using a standard checklist.⁴ (So this experiment, you will notice, was immune from the criticism that stress might have affected the subjects’ sickness-related behaviour as opposed to their actual health.)

The results of Cohen’s experiment were clear and compelling. The more psychological stress an individual reported having been exposed to in the past, the greater their chances of infection with cold viruses and, once infected, the greater their chances of developing a clinical cold. Both the risk of viral infection and the risk of developing clinical symptoms increased in direct proportion to the amount of stress.

The correlation between stress, infection and illness was impressively strong. Individuals with the highest stress ratings were six times more likely to be infected with cold viruses than those with the least stress, and twice as likely to develop a cold. Moreover, these associations between stress, infection and illness held up even after the data had been adjusted statistically to remove any effects of other potentially relevant factors, including the subjects’ age, sex, prior health, allergies, smoking and drinking habits, sleep and exercise patterns, diet, weight and education.

The technique of deliberately exposing the subjects to viruses ensured that they all had an equal opportunity to be infected. But you can be exposed to viruses without being infected. When you travel in a crowded train or bus you are regularly showered with exotic bacteria and viruses, but fortunately infection does not inevitably follow. Most of the time the bugs fail to make it past your skin or penetrate your inhospitable orifices. To establish that you have actually been infected it must be possible to recover viruses from your blood or body fluids, or show that your immune system has generated antibodies against the virus.

Exposure to viruses and subsequent infection are not the only steps along the path to illness, however. Not every infection develops into a clinical disease. The number of colds you will suffer in a lifetime represents a minuscule fraction of the number of cold virus infections you have had.

Detailed analysis of this experimental data enabled Cohen and his colleagues to tease apart the influences of stress on these two distinct components of disease. Whether or not someone was infected by the cold viruses depended primarily on how they were feeling at the time, especially their current perception of stress and negative emotions. But once they had been infected their chances of going on to develop a clinical cold depended more on their previous exposure to stressful life events than their current emotional state.

These results illustrate a general point: an individual’s psychological state can exert different influences on the various steps in the pathway to disease, from initial exposure to disease-causing viruses or bacteria, through infection by those viruses or bacteria, to the development of disease symptoms and the behavioural response to those symptoms.

We have sampled some of the extensive evidence that what goes on in people’s minds really does affect their chances of becoming ill or dying. The next question is how. It is time to consider the question of mechanism.

3 Psyche’s Machine: The Inside Story

Her pure and eloquent blood

Spoke in her cheeks, and so distinctly wrought,

That one might almost say, her body thought.

John Donne, Of the Progress of the Soul,

‘Second Anniversary’ (1612)

By what means does the mind influence human susceptibility to disease? How can insubstantial thoughts or emotions produce a cold, let alone heart disease or cancer? After all, colds are caused by viruses not thoughts. We have seen evidence that our mental and physical states affect each other; what we need now is an explanation of how they do this. We need a mechanism.

In this chapter we shall explore the biological and psychological pathways by which the mind influences physical health – and, as we shall see, how physical health in turn influences the mind. This is the inside story of how the mind and body interact. There are three main strands to this story. First, our minds can make us believe we are ill, whether or not we really are ill in any objective, clinical sense. Our psychological and emotional state affects our perception of bodily symptoms and our reaction to those symptoms. This is the familiar (and generally misleading) connotation behind terms such as ‘psychosomatic’. But the mind does more than influence our perception of physical wellbeing: it can genuinely affect our physical health. We come now to the second and third strands of the story.

The mind impinges on physical health in two fundamentally different ways: through our behaviour and, more directly, through our body chemistry. Psychological and emotional factors can lead us to behave in unhealthy or self-destructive ways which increase the risks of disease, injury or death. Smoking is an obvious example. Meanwhile, beneath the surface, our mental state can alter our susceptibility to disease by influencing the body’s biological defence mechanisms, most notably the immune system.

The perception of sickness

There is a fundamental distinction between illness – the sufferer’s belief that something is wrong with them – and disease, which is a definable medical disorder that can be objectively identified according to agreed criteria. You can have a disease (such as early-stage cancer or coronary heart disease) yet not feel ill. Conversely, you can feel ill even though a doctor cannot detect any evidence of disease.

Many people who end up presenting themselves to a doctor have no identifiable organic disease. There is apparently nothing physically wrong with them. Yet they are still there in large numbers, claiming (and, in most cases, genuinely believing) that they are unwell. They are often referred to in rather loaded terms as ‘the worried well’. But the majority of those who are suffering from vague, undiagnosed illnesses are not malingering. They really do feel ill and their ability to lead a normal life may be significantly impaired.

According to a report by the Royal College of Physicians and the Royal College of Psychiatrists, as many as half of all those who present themselves as out-patients for ostensibly medical reasons are suffering from psychological problems. Although they have physical symptoms such as pains, palpitations or breathlessness they have no detectable physical disease. Doctors perhaps understandably focus on the physical symptoms rather than the psychological problems. One consequence is that huge amounts of time and money are wasted on diagnostic tests and treatments for elusive diseases.

A substantial proportion of patients – a fifth or more – prove very difficult for doctors to deal with. Either their illness cannot be diagnosed at all, or, when a diagnosis is proposed, they find it unacceptable. Their treatment, if any, is frequently ineffective and they keep returning to the doctor over and over again, distressed and dissatisfied. These are the so-called heartsink patients. To make sense of what is going on we must once again turn to the mind.

Health and illness lie along a continuum. Often the dividing line between the two is arbitrary, and as much a reflection of our perceptions and expectations as it is of our true state of physical health. Our psychological and emotional state affects our sensitivity to bodily symptoms, our perception and interpretation of those symptoms and, finally, our propensity to seek medical help – whether or not those symptoms reflect a genuine disease.

Those who seek medical care do so because they have noticed certain symptoms, concluded that these symptoms constitute a real or potential illness, and decided to take action. Each of these steps is open to psychological and emotional influences. Individuals differ enormously in the extent to which they monitor their own health; in their willingness to put up with pain, discomfort and worry; and in their readiness to do something about it. The processes that culminate in a decision to visit the doctor depend on factors that are unique to each individual, including their social and financial circumstances, personality, experience, cultural background and genetic make-up. A lot can also depend on their current psychological and emotional state.

When a person is stressed or anxious they may become preoccupied with their health. There is a greater likelihood that they will notice (or imagine) physical symptoms; interpret those symptoms as indications of disease; and become sufficiently anxious about them to visit a doctor. They may also be more in need of the personal attention that they are perhaps not getting from others.

The heightened arousal that accompanies anxiety can make subtle bodily symptoms more noticeable. Moreover, the physiological changes that often accompany anxiety, such as headaches, churning guts or palpitations, may be interpreted as symptoms of disease. The mind can unconsciously create a medical mountain out of a molehill.

Our own perceptions are not the only ones that matter when it comes to assessing our state of health. The perceptions of those around us can also play an important role. Social pressures can reinforce, or even create, the perception that we are ill.

Imagine you are under a lot of stress. (Perhaps you don’t have to imagine.) You have been told you are going to lose your job, your partner has left you and your personal finances are in meltdown. Unless you are exceptionally self-possessed your behaviour patterns will change noticeably. Perhaps you no longer relish the prospect of going for a drink with your friends; you feel depressed so you decline social invitations; you sleep badly and come to work looking tired; you are preoccupied with your problems and your performance accordingly suffers; you become irritable or keep bursting into tears; you go off your food and lose weight, or perhaps you turn to comfort feeding and pile on the calories instead.

Your friends and colleagues notice these changes and comment on them. They keep remarking that you don’t look well; it must be the stress; perhaps you should see a doctor. Come to think of it, you don’t feel too marvellous. Those headaches and the constant fatigue might be significant, and you have lost weight.

Before long you have convinced yourself that you are ill. You have certainly read enough magazine articles to know that stress is bad for your health. You take to your bed, or perhaps you trot off to see your doctor. To put it in the language of social psychology, social pressures have encouraged you to take on the ‘sick role’. Now, you may indeed be genuinely ill; as we shall see, there is no doubt that stress can make us more susceptible to disease. But the thought processes that have led you to the conclusion that you are ill were driven largely by social pressure. Other people’s minds, as well as your own, were involved in the process.

Consider, for example, the case of Colin Craven – the hypochondriac from hell in Frances Hodgson Burnett’s children’s classic The Secret Garden.

The obnoxious, bedridden Colin has been treated as an invalid, doomed to an early death, for all of his ten years. Everyone in Colin’s orbit unquestioningly accepts that he is destined to be a crippled hunchback – that is, if he lives at all. They continually reinforce Colin’s belief in his illness, reminding him of his weakness and urging him to rest. As one would expect, lying in bed all day has had a seriously debilitating effect on Colin’s muscles; on the rare occasions when he does get up he feels genuinely feeble.

The egregious brat lies in bed all day with the family retainers pandering to his every whim. The servants live in fear of Colin’s hysterical tantrums and dare not contradict him. The housekeeper privately recognizes that Colin is a victim of self-indulgence and hypochondria but would not dream of saying this to his face. To make matters worse, Colin’s doctor is next in line to inherit the family property should Colin die and is therefore less than objective about the child’s health. A London doctor who has had the temerity to suggest that Colin is not ill has been studiously ignored. Colin is immersed in his all-consuming hypochondria and sublimely unaware of how spoilt and unreasonable he is. Until his cousin Mary arrives.

Mary (who is not the nicest of children herself) rubbishes Colin’s alleged medical condition during a fit of pique. She tells Colin bluntly that he has no trace of a lump on his back and is just being hysterical.

By challenging the unquestioned belief in Colin’s illness, Mary has an electric effect on him. The supposed invalid soon comes to realize that there isn’t anything wrong with him beyond his morbid state of mind. There is no lump on his back; he is thin and pallid because he refuses to eat properly; and he is weak because he lies in bed all day.

So long as Colin shut himself up in his room and thought only of his fears and weakness and his detestation of people who looked at him and reflected hourly on humps and early death, he was a hysterical, half-crazy little hypochondriac who knew nothing of the sunshine and the spring, and also did not know that he could get well and stand upon his feet if he tried to do it. When new, beautiful thoughts began to push out the old, hideous ones, life began to come back to him, his blood ran healthily through his veins and strength poured into him like a flood.

With the help of cousin Mary, her rosy-cheeked proletarian chum Dickon and, of course, the Secret Garden, Colin is soon transformed into a ‘laughable, loveable, healthy young human thing’ who announces to the world that he is going to ‘live for ever and ever and ever’.

A more delicate literary example of an indeterminate illness born of circumstance can be found in Tolstoy’s Anna Karenin. Young Kitty Shcherbatsky declines an offer of marriage from the worthy but unworldly Levin, expecting instead to receive a proposal from the dashing Count Vronsky. When Vronsky’s anticipated proposal fails to materialize, Kitty, like a good nineteenth-century heroine, goes into a severe physical and mental decline which lasts for months. It is serious stuff and everyone is worried about the poor girl’s health. Kitty’s family doctor discusses her condition with a celebrated specialist whose help has been enlisted by the worried family:

‘But of course you know that in these cases there is always some hidden moral and emotional factor’, the family physician allowed himself to remark with a faint smile.

‘Yes, that goes without saying’, replied the celebrated specialist …

Kitty’s family and friends are worried even though they are well aware that her condition has essentially psychological origins. Kitty is described as ‘ill for love of a man who had slighted her.’ Kitty’s health does not improve and it is feared that she might actually die. Her anxious parents therefore take her on a foreign tour, where she encounters another young lady whose illness is also ‘due to a love affair’. The passage of time and the distractions offered by foreign travel eventually bring about Kitty’s recovery. Her illness and absence also allow circumstances to develop in her favour; she returns to Russia, marries the faithful Levin and (unlike the eponymous Anna) lives happily ever after.

Another way in which mental processes intrude into the domain of physical health is through the universal need for legitimacy. When we have decided that we are ill we want other people, and especially our doctor, to accept that we really are ill and not just malingering or being neurotic. Whether consciously or unconsciously, we want our putative disease to be accepted as genuine and not dismissed as a product of our fevered imagination. We need to legitimize our sickness by presenting the doctor with symptoms that will be accepted as evidence of a known organic disease. After all, no diagnosis means no treatment. As we saw in chapter 1, this can be a real problem for those suffering from poorly understood and controversial disorders such as chronic fatigue syndrome.

In his fascinating historical study From Paralysis to Fatigue, Edward Shorter has described how the physical symptoms that characterize so-called psychosomatic illnesses – those vague, undiagnosable ailments whose physical causes prove so elusive – have evolved over the years to keep pace with changing ideas about what constitutes a genuine disease. As society’s perceptions and beliefs about disease have changed, so the symptoms of psychosomatic illness have also changed to keep pace with what is regarded as legitimate evidence of disease. Thus, in the eighteenth and nineteenth centuries it was common for people to succumb to hysterical paralysis, convulsions or ‘fits of the vapours’. Paralysis of the legs was positively de rigueur among well-to-do young ladies of the nineteenth century. Nowadays, some would regard the symptoms of chronic fatigue and allergies as falling into the same category.

Shorter’s historical analysis is interesting in that it demonstrates the powerful effect social pressures and cultural norms can have on patterns of symptoms. Actual diseases are another matter, however. There is nothing imaginary or unreal about many cases of chronic fatigue syndrome, allergies or other supposedly fashionable illnesses.

Our expectations also have an important influence on our perception of health. In industrialized societies like Britain and the USA general expectations of health have risen considerably in recent decades and continue to rise. As in so many other spheres of human activity, a consumerist attitude towards health has become the norm. People demand more in terms of their physical and mental wellbeing and are less willing to tolerate minor health problems which detract from their quality of life. That elusive – and probably illusory – gold standard of total health is increasingly demanded as of right even though, to quote one expert, ‘deviance, clinically or epidemiologically defined, is normal’. This emphasis on positive health, as opposed to the mere absence of disease, is reflected in the explosion of interest in complementary or alternative medicine.

Huge advances in living conditions and medical knowledge have brought about large increases in life expectancy in many countries during the course of the twentieth century. Yet despite this we are apparently a sick bunch and getting sicker – if, that is, we define sickness in terms of perceptions and behaviour as opposed to objective measures of physical health.¹ Studies conducted in the USA in the late 1920s found an average of eight reported episodes of sickness for every ten people surveyed over a period of several months, whereas in the early 1980s the comparable figure was twenty-one sicknesses: an increase of 160 per cent. If we define sickness as seeking medical attention then the average person nowadays is ‘sick’ more than twice a year, compared with less than once a year in the 1920s. To be sick is normal.

Of course, what has increased over the decades is not the true incidence of diseases: it is our sensitivity to aches and pains; our tendency to ascribe them to physical diseases; our reluctance to put up with them; and our readiness to seek expert medical care.

Perish the thought, but just occasionally some of us have been known to concoct a tactical minor illness to get ourselves out of a predicament – perhaps as an excuse to avoid a dire social occasion or, less blatantly, to justify our poor performance in an exam, at work or in our personal relationships. Outright lying need not be involved. Gentle self-delusion is all that is needed. When sickness becomes an escape route from an unpleasant situation or embarrassment it is all too easy to convince ourselves that the symptoms are genuine. The ‘sore throat’ that conveniently gets the anxious child out of having to perform in the school concert can feel like a real sore throat.

Our minds, like Colin Craven’s, can exaggerate the severity and significance of symptoms, causing us unnecessary distress and wasting doctors’ time. But perceptions can shift in the opposite direction as well. An inert placebo ‘drug’ will often produce startling improvements in a patient’s symptoms – provided the patient believes it to be a real medicine and expects it to have a beneficial effect. (We shall be revisiting the placebo effect later; it is yet another example of why the mind cannot be divorced from bodily health, even when we are dealing with apparently straightforward physical diseases.)

We all have the capacity unconsciously to blot out things we find too uncomfortable or upsetting to think about. This psychological defence mechanism is known as denial. However, the mind’s ability to belittle or even ignore symptoms is something of a mixed blessing. Being excessively stoical or negligent about your own health is risky.

When people react to illness by denying the reality of their symptoms they may save themselves the unpleasantness of confronting an unpalatable reality. But their denial can be positively dangerous if it prevents them from seeking timely medical attention. A woman who fails to notice a lump in her breast, for example, or chooses to disregard it until her breast cancer is at an advanced stage, may pay for her insouciance with her life.

It is an unfortunate fact that people are less likely to seek medical help if it is difficult, inconvenient or embarrassing for them to do so – perhaps because they are too busy, or cannot afford the fees, or because they are simply afraid of calling a doctor out on a false alarm. Heart attacks are notoriously more likely to prove fatal at weekends, when it is inconvenient or potentially embarrassing to seek expert medical help. The lives of countless heart attack victims might have been saved had they not incorrectly attributed their chest pains to indigestion.

The disastrous consequences of denial are sombrely portrayed in Arnold Bennett’s Riceyman Steps. The tightfisted Clerkenwell bookseller Henry Earlforward has cancer of the stomach but steadfastly denies that he is ill. Earlforward insists that it is merely a temporary indisposition and that he has a constitution of iron.

For a long time Earlforward’s wife interprets his lack of interest in food as a symptom of his miserliness rather than any medical problem. Even when it becomes obvious that the emaciated bookseller is gravely ill he obstinately refuses to be examined by a doctor, let alone admitted into hospital. His wife rails at him for concealing from her the seriousness of his illness until it is too late to do anything about it. She tries hard to persuade Henry to accept medical help, but is forced to concede for ‘nobody can keep on fighting a cushion for ever’. Faced with Henry’s bland obstinacy, his wife and doctor eventually abandon their attempts to help him and he dies from his cancer – a victim of his own misplaced psychological defences.

Whether or not an illness has psychological origins it will certainly have psychological consequences. Feeling ill for any length of time is a psychologically debilitating experience. One of the simple but important ideas I hope to convey in this book is that the relationships between mind, body and disease work both ways. The mind affects the body and hence physical health. Conversely, physical health affects the mind and hence our thoughts, emotions and behaviour.

All but the most trivial of illnesses produce some sort of emotional reaction, whether it be mild irritation, anxiety, anger, denial or depression. Other things being equal, a serious illness should provoke a more intense emotional reaction than a minor illness. But other things seldom are equal. Illness means different things to different people, and just because an illness is not life-threatening this does not mean the sufferer will be emotionally untouched by it. An individual who has never before experienced any significant illness, pain or discomfort may be upset by relatively minor symptoms which would seem insignificant to someone who has suffered a string of serious diseases.

Our emotional responses to illness can have a crucial bearing on our recovery and future health. If being ill makes us depressed we may become careless about adhering to our doctor’s advice or taking our medicine. This may, in turn, impede recovery. Whether or not a cancer patient adheres strictly to a programme of radiotherapy or chemotherapy can have a major impact on their chances of survival. There are patients who simply give up and sink into decline.

In extreme cases the emotional reaction to an illness can prove a bigger problem than the illness itself. Severe depression is far more debilitating and intrusive than many physical ailments. As we shall see in the next chapter, severe depression can also have detrimental effects on immune function and subsequent health, creating a spiral of decline. Doctors and patients ignore the psychological and emotional consequences of illness at their peril.

Finally, please do not go away with the impression that an individual’s perception of their own health is an entirely meaningless or deceptive index, indicating only their degree of hypochondria. On the contrary. Research has shown that in certain respects perception is a good guide to reality. Although our subjective judgement is not always an accurate index of our current state of health, it does provide a reasonably good predictor of our long-term risk of dying prematurely. Depressing though it may be if you are an arch hypochondriac, the research indicates that people who believe they are unhealthy do die younger on average. Moreover, perceptions are clearly important for practical and economic reasons: people’s perceptions of their health, rather than objective measures of health, are what largely determine their initial usage of medical facilities.

Bad behaviour

Sex and drugs and rock and roll

Is all my brain and body need

Ian Dury, ‘Sex and Drugs and Rock and Roll’ (1977)

A cousin of mine who was a casualty surgeon in Manhattan tells me that he and his colleagues had a one-word nickname for bikers: Donors. Rather chilling.

Stephen Fry, Paperweight (1992)

Our minds can have a profound impact on the physical health of our bodies by altering the way we behave. Psychological and emotional factors can dispose us to do all manner of unhealthy and self-destructive things. The self-destruction may be absolute and abrupt, as in suicide or fatal accidents, or gradual and cumulative, as in smoking.

Stress and anxiety, for example, can prevent us from sleeping properly and make us more inclined to smoke, drink excessive amounts of alcohol, eat too much of the wrong sorts of food, omit to take our medicine, neglect physical exercise, consume harmful recreational drugs, indulge in risky sexual behaviour, drive too fast without wearing a seat belt, have a violent accident, or even commit suicide (though not usually all at once).

Anna Karenin offers an impressive catalogue of self-destructive behaviour engendered by psychological and emotional trauma. Anna abandons her husband, the colourless bureaucrat Karenin, for the dynamic Count Vronsky. But their love is doomed and the emotional pressures on Anna build up to a fatal climax.

As a preamble to her eventual self-destruction, Anna nearly dies giving birth to Vronsky’s illegitimate daughter. In what she thinks are her final hours Anna appears to reconcile herself with her husband. Mad with emotional torment at this turn of events, Vronsky goes off and shoots himself – but not fatally. Although Vronsky is an army officer, and therefore presumably capable of hitting his own heart at point blank range, the bullet misses. He is seriously wounded – enough to make it a meaningful parasuicidal gesture – but does not die. Anna and the baby go to live with Vronsky, but her husband refuses to divorce her and she becomes a social outcast. The strain of her position renders Anna increasingly unstable and she develops paranoid delusions about Vronsky’s supposed unfaithfulness. Consumed by the madness of her passion, Anna suddenly decides that she must end her torment and punish Vronsky for his imagined misdeeds by killing herself. Anna famously ends her own life under the wheels of a train:

‘There,’ she said to herself, looking in the shadow of the trucks at the mixture of sand and coal dust which covered the sleepers. ‘There, in the very middle, and I shall punish him and escape from them all and from myself.’

And she does. And there is more. Almost insane with grief at Anna’s death, the bereaved Vronsky volunteers to fight, and very probably die, in a war between the Serbians and the Turks. Vronsky no longer places any value on his life and relishes the prospect of death: ‘I am glad there is something for which I can lay down the life which is not simply useless but loathsome to me. Anyone’s welcome to it …’

The melodrama of Anna Karenin’s suicide and Vronsky’s death wish are positively restrained in comparison with the high-camp posturings of Werther, the suicidal hero of Goethe’s The Sorrows of Young Werther. This eighteenth-century piece of unfettered Teutonic sentimentality tells the tragic tale of an unbalanced youth who tops himself after a bad dose of unrequited love.

The story is a simple but eternal one. Werther loves Lotte. Oh, how he loves her! But, alas, he cannot have her. Lotte is already promised to the worthy Albert and soon marries him, leaving Werther to wallow in emotional excess. He sheds a thousand tears one moment and ‘overflows with rapture’ the next, and each step on the way is recounted in copious letters to his long-suffering chum Wilhelm. So it comes as no surprise that, denied his one true love, Werther decides to end it all. Characteristically, his suicidal decision is reached only after much beating of chest, gnashing of teeth, shedding of tears and general languishing in melancholy, during which time an unkind reader might be forgiven for urging the lad to get on with it. Even when Werther finally does get round to pulling the trigger he takes several hours to die.

Incidentally, the tragic tale of young Werther had a fairly profound effect on the health of a number of readers. So resonant was Goethe’s writing with the romantic spirit of the times that the book triggered an epidemic of copy-cat suicides and was consequently banned in many places.²

All the leading causes of death in industrialized nations – including heart disease, cancer, accidental injury and AIDS – depend to some extent on how we behave. Smoking, eating habits, alcohol consumption, physical exercise, sleep patterns, sexual behaviour and choosing to wear a seatbelt, to name but a few, have ramifications for our health and wellbeing.

In industrialized societies, for example, accidental injuries and violence now account for at least half of all deaths among young men: a fact that is not wholly unrelated to the behavioural characteristics of young men. In extreme cases people who are very depressed or upset commit suicide or deliberately behave in a way which invites serious injury or death. Severe depression can lead to self-destructive behaviour. Besides making us act in positively unhealthy ways, psychological factors like anxiety, stress or depression can also inhibit us from engaging in activities that are beneficial to health, such as physical activity or social relationships with others.

In certain cases, such as crashing your car or committing suicide, the causal connection between behaviour and the subsequent damage to health is pretty obvious and requires no intimate knowledge of medical science to understand. Thanks to education and constant repetition in the media, less obvious connections between behaviour and health are also now widely recognized. The public accept that there are links between smoking and all manner of fatal diseases; between slothfulness and heart disease; between alcohol abuse and cirrhosis; and between unprotected sex and AIDS.

A stark illustration of how behaviour affects health is provided by AIDS. There are enormous geographical variations in the incidence of HIV infection and AIDS. For example, the incidence of AIDS in Honduras is fourteen times higher than in neighbouring Guatemala. Even within a single country or a single city there are massive variations in rates of infection between different social groups.

Since the HIV retrovirus was discovered to be the causal agent for AIDS in 1983 it has become clear that these large variations result primarily from differences in people’s behaviour – especially their sexual behaviour, which remains the route by which the virus is transmitted in the vast majority of HIV infections. It is generally accepted that a practical vaccine or cure for HIV/AIDS is at least a decade away.³ In the meantime, the only effective means available for limiting its spread is to change the way we behave.

There are plenty of commonplace behaviour patterns that kill people gradually but in huge numbers. Smoking is the prime example. As long ago as 1604 King James I, in his treatise A Counterblast to Tobacco, did not exactly pull his punches when he described the new-fangled habit of smoking as:

A custom loathsome to the eye, hateful to the nose, harmful to the brain, dangerous to the lungs, and in the black, stinking fume thereof, nearest resembling the horrible Stygian smoke of the pit that is bottomless.

Smoking is the riskiest thing that most people will ever do in their lives. At present, smoking-related diseases account for 15–20 per cent of all deaths and result in over 100,000 premature deaths every year in Britain alone. Smoking greatly increases the risk of lung cancer, now the commonest fatal cancer in Britain. Smokers are ten times more likely to die from lung cancer than non-smokers and around 90 per cent of lung cancers are attributable to smoking.

Smoking also increases the risks of various other fatal or debilitating diseases including coronary heart disease (the biggest cause of death in most industrialized countries), chronic bronchitis, emphysema, and cancers of the oesophagus, bladder and pancreas. A quarter of all deaths from coronary heart disease are smoking-related. As if that were not enough, smoking causes birth complications and doubles the risk of a pregnant woman miscarrying.

Think about these statistics from the British Medical Association. The average risk that you will die from leukaemia within the next year is about 1 in 12,500. The average risk that you will die in a vehicle accident is 1 in 8,000. If you are, say, forty years old, your risk of dying from natural causes of any sort during the next twelve months is 1 in 850. However, if you smoke ten cigarettes a day your odds of dying within the year are 1 in 200. Or look at it another way: take a random sample of a thousand young men who smoke; on the basis of actuarial data it can confidently be predicted that one of these young men will eventually be murdered, six will be killed on the roads and two hundred and fifty will die prematurely from the effects of smoking.

Smoking is clearly bound up with what goes on in people’s minds. The reasons why individuals start smoking and why they then find it impossible to quit are neither simple nor well understood. Psychological studies of smokers have, however, confirmed the truth of several common assumptions.

It is indeed true that people who are depressed or stressed are more likely to smoke (and, consequently, more likely to die from lung cancer). Smokers really do experience a stronger desire to smoke at times of heightened anxiety. To add to their problems, psychological stress is associated with a higher failure rate among smokers trying to kick the habit. One long-term study of smokers found that individuals who had been depressed as much as nine years earlier were 40 per cent less likely to be successful in their attempts to give up smoking.

It gets worse. The psychological and emotional factors that make people inclined to smoke induce them to do other unhealthy things as well. Research has shown that moderate-to-heavy smokers are, on average, significantly less conscious of health-related issues, hold less favourable attitudes towards healthy behaviour and have a generally less healthy lifestyle in comparison with non-smokers or light smokers. (Conversely, wholesome behaviour patterns also come in clusters; researchers at Harvard University Medical School found that individuals who drank only decaffeinated coffee also tended to eat lots of vegetables, take regular exercise and wear their seatbelts.)

As well as prompting people to smoke, stress is also linked to increased alcohol consumption – at least, in certain types of individual. The health implications of excessive drinking can be profound. Approximately 20 per cent of all male in-patients in British hospitals have alcohol-related problems. Alcohol can rot people’s livers and kill them in drunken accidents (though alcohol is not the only recreational drug capable of damaging health: there is reasonably good evidence, for example, that marijuana impairs the immune system, with potentially adverse consequences for the health of long-term users.)

The perils of the grape are amusingly described in Othello. The scheming Iago lures the unwitting Cassio into getting steamingly drunk, as a result of which Cassio lands himself in serious trouble and loses his job. On sobering up, Cassio bemoans the loss of his reputation and curses the demon drink:

‘Drunk! And speak parrot! And squabble! Swagger! Swear! And discourse fustian with one’s own shadow! O thou invisible spirit of wine, if thou hast no name to be known by, let us call thee devil! … O God, that men should put an enemy in their mouths to steal away their brains! That we should with joy, pleasance, revel and applause, transform ourselves into beasts!’

Literature is amply stocked with characters who drink themselves into an early grave in reaction to emotional crisis or unhappiness. There are roistering drunks who drink to escape boredom or poverty, like J. P. Donleavy’s Ginger Man, Sebastian Dangerfield. There are determined drunks who drink to escape from grief. In Wuthering Heights, the unfortunate Hindley Earnshaw becomes a hopeless alcoholic after the death of his wife (from consumption, naturally) and drinks himself into the grave by the age of twenty-seven. And there are aimless drunks who drink to forget their own pointlessness. In F. Scott Fitzgerald’s The Beautiful and Damned, for example, we have Anthony Patch, an independently wealthy and well-educated young man blighted by indolence, boredom and melancholy. A turbulent marriage and self-imposed idleness push him into self-destructive alcoholism and he degenerates into ‘Anthony the poor in spirit, the weak and broken man with bloodshot eyes’.

Incidentally, when it comes to self-destruction by alcohol the track record of doctors is almost unrivalled. As a profession, they rank second only to pub-owners and bar staff in the league table of deaths from alcohol-related liver disease. Doctors are 3.4 times more likely than the average worker to die from cirrhosis of the liver. According to one 1995 estimate, as many as one in twelve British doctors is addicted to alcohol, drugs or both, thanks mainly to the enormous stress the majority of them are constantly under. (But I should not be too smug about this statistic because ‘literary and artistic workers’ also fare badly, with twice the average death rate from cirrhosis.)

On the other hand, moderate alcohol consumption can be an effective buffer against stress – and here again science has only of late managed to verify thousands of years’ worth of everyday experience. Psychological studies have confirmed what countless millions of people have discovered for themselves, namely that when we are under stress we often feel less anxious if we drink alcohol. (A moderate intake of alcohol also appears to reduce the risk of coronary heart disease, but that is another story.) Sir Winston Churchill’s opinion was clear: ‘I have taken more out of alcohol than alcohol has taken out of me.’

There is nothing surprising about the fact that alcohol has its good side. It has, after all, been an intimate part of human life since the dawn of civilization. Alcohol was in use for medicinal purposes (in the literal rather than euphemistic sense) over four thousand years ago and was probably quaffed for recreational purposes long before that.

Opinions differ as to when exactly humans first discovered the joys of booze, but there is evidence that wine was being drunk in Transcaucasia eight thousand years ago – long before the wheel was invented. Some authorities have argued that Stone Age man was cultivating vines as early as ten thousand years ago. Wine growing was well established in the Middle East by 4000 BC and was an integral part of daily life in ancient Egypt and Mesopotamia. It says something that wine is mentioned 150 times in the Old Testament.

Then there are the social benefits of communal drinking to add to the purely pharmacological pleasures of alcohol. Samuel Johnson spoke for many when he declared that: ‘There is nothing which has yet been contrived by man, by which so much happiness is produced as by a good tavern or inn.’

Yet the things that give us pleasure carry risks, and we are very poor at assessing those risks. While we consistently overestimate the dangers posed by rare or exotic threats like plane crashes, murders, nuclear accidents or shark attacks, we tend to disregard the risks of common killers like heart disease and vehicle accidents. We are especially prone to underestimating the risks arising from our own behaviour, such as smoking, travelling in cars, abusing alcohol or having unprotected sex.

Smokers now acknowledge the unappetizing fact that their behaviour significantly increases their risk of dying prematurely from heart disease or cancer. Nevertheless, psychological research has established that they seriously underestimate the magnitude of that risk. There is a consistent ‘optimistic distortion’ of perceived health risks among smokers; they know smoking is bad for them but they do not recognize just how bad. No matter how often the statistics are quoted they do not seem to sink in. One reason why the health consequences of smoking have such a muted impact on people’s perceptions is the large delay, often measured in decades, between starting to smoke and falling ill.

If you should happen to be an overweight, tobacco-addicted, boozing, couch potato who loves fried food, you can take a few crumbs of comfort from the fact that others’ attempts at healthy living can backfire. Dieting, for example, almost invariably fails to bring about the desired result of sustained weight loss. The sense of personal failure that comes as the scales lurch upwards again can produce a damaging drop in self-esteem and a sense of losing control; the frustrated dieter’s response may be to abandon the diet and thus swing back to even greater porkiness. Mother Nature also conspires against the earnest dieter. People whose body weight oscillates because of dieting have a greater risk of premature death from coronary heart disease or other causes. Unsuccessful dieting can be bad for your health – and most dieting is ultimately unsuccessful.

What of behavioural self-destruction in literature? Fiction is littered with protagonists who recklessly expose themselves to danger, neglect their health or run themselves into an early grave because of great unhappiness or emotional turmoil.

An early case history of self-destruction appears in Le Morte d’Arthur, Sir Thomas Malory’s fifteenth-century version of the legends of King Arthur and the knights of the Round Table. It is the sad tale of the Fair Maiden of Astolat and her doomed love for Sir Launcelot.

The brave, noble, irresistibly attractive Sir Launcelot rides to Astolat en route to a joust, and stays the night there at the home of the elderly baron, Sir Bernard of Astolat. Sir Bernard has a beautiful and virginal young daughter, the Fair Maiden of Astolat, who is at once smitten by Sir Launcelot. She is, as Malory so engagingly puts it, ‘hot’ in her love for the noble knight: ‘for he is the man in the world that I first loved, and truly he shall be last that ever I shall love.’ (Astolat, by the way, is Guildford and the maiden’s name is Elaine. Fortunately, ‘The Fair Maiden of Astolat’ has more Arthurian resonance than ‘Elaine of Guildford’.)

Sir Launcelot is grievously wounded and the Fair Maiden goes to look after him. Night and day she tends him, until his wounds are healed and Sir Launcelot is ready to take his leave. The Fair Maiden of Astolat beseeches Sir Launcelot to marry her or, failing that, at least go to bed with her. But the upstanding knight will not countenance marriage and refuses to dishonour the Fair Maiden by indulging in extramarital frolicking. She begs him again to be her husband or her lover, but to no avail. ‘“Alas,” said she, “then must I die for your love.”’ The noble knight leaves Astolat to get back to some real man’s work (fighting), leaving the emotionally wrecked Fair Maiden of Astolat behind him. Her mental state and self-destructive behaviour soon wreak havoc upon her physical health:

Now speak we of the Fair Maiden of Astolat that made such sorrow day and night that she never slept, ate, nor drank … So when she had thus endured a ten days, that she feebled so that she must needs pass out of this world, then she shrived her clean, and received her Creator … ‘it is the sufferance of God that I shall die for the love of so noble a knight … I loved this noble knight, Sir Launcelot, out of measure, and of myself, good Lord, I might not withstand the fervent love wherefore I have my death.’

True words from the Fair Maiden of Astolat, because very soon she dies. Clutched in her hand is a letter proclaiming her love for Sir Launcelot. That love has sent the Fair Maiden to her death, a death achieved through her behaviour.

Reckless behaviour allied with emotional distress can destroy an individual’s physical health, as illustrated in Jude the Obscure, Thomas Hardy’s novel about ‘a deadly war waged between flesh and spirit’.

Jude Fawley, a self-educated young man of lowly origins, aspires to leave his unlovely country village and enter the hallowed portals of Christminster (Oxford) University. But the restrictions imposed upon Jude by class and poverty mean that he must instead make his way as a humble stonemason. Jude’s romantic life is as frustrating and unsuccessful as his academic life. After being trapped into an ill-fated marriage to a pig-breeder’s daughter he falls in love with his cousin Sue. The two are drawn together by an almost mystical affinity, but Sue leaves him to marry an older man. The two lovers are eventually united and live together, unmarried and condemned by society, in poverty and unhappiness. In the end Jude loses Sue, who returns to her husband.

Having failed to fulfil both his intellectual and romantic desires, Jude goes into physical and mental decline. Like many a nineteenth-century tragic hero, he succumbs to a consumptive illness which proves to be terminal. Jude’s behaviour exacerbates his medical condition. With careless disregard for his health he makes a long journey on foot in the pouring rain to see Sue for the last time. She rejects his pleas and he returns to Christminster, physically and emotionally broken. But, as Jude explains to his former wife, he was fully aware of the risk to his health when he undertook the journey:

I made up my mind that a man confined to his room by inflammation of the lungs, a fellow who had only two wishes left in the world, to see a particular woman, and then to die, could neatly accomplish those two wishes at one stroke by taking this journey in the rain. That I’ve done. I have seen her for the last time, and I’ve finished myself – put an end to a feverish life which ought never to have begun!

Eventually he dies, alone and neglected, not yet thirty years old. Hardy implicitly takes a multi-causal view of Jude’s final illness, since environmental and constitutional factors play a role in it, together with psychological stress.⁴ His emotional distress at losing Sue and at the death of their children acted as a trigger, but the illness also has antecedents in Jude’s weak constitution and the harsh conditions he endured during his time as a stonemason:

I was never really stout enough for the stone trade, particularly the fixing. Moving the blocks always used to strain me, and standing the trying draughts in buildings before the windows are in, always gave me colds, and I think that began the mischief inside.

Most of us die sooner than we have to because of the way we behave and the choices we make. Personally, though, I have some sympathy with Publilius Syrus, who two thousand years ago expressed the opinion that: ‘They live ill who expect to live always.’

Mind over immune matter

In this struggle Tarrou’s robust shoulders and chest were not his greatest assets; rather, the blood which had oozed under Rieux’s needle and, in this blood, that something more vital than the soul, which no human skill can bring to light.

Albert Camus, The Plague (1947)

We turn now to a less visible, but no less important, mechanism by which the mind and body interact to affect health: the immune system. Among the most important developments in recent years has been the discovery of numerous biological pathways connecting the brain with the body’s defence and regulatory mechanisms. Through these pathways the biological system that underlies our thoughts, emotions and behaviour – the brain – can exert a pervasive influence on the biological system that defends the body against most forms of disease – the immune system.

Our physical health depends critically on how well our immune system is functioning. One reason why a person suffering from psychological stress is more susceptible to colds and infections is because their immune system is less able to resist when they are exposed to disease-causing viruses or bacteria. In the following chapters we shall be exploring the manifold ways in which the mind and immune system affect each other. But before we do this we need to clarify a few basic issues.

So far I have referred rather sweepingly to the mind’s effect on the immune system, as though the immune system were a homogeneous entity whose activities could be measured in a simple way, like temperature or blood pressure. In reality, the immune system is a breathtakingly complex and subtle entity whose intricate workings are still far from being fully understood. Immunology is one of the branches of science that has made the most spectacular leaps in understanding over the past thirty years, but it still has a very long way to go. To unravel how the mind influences physical health we must first establish what the immune system does and how it works.

UNDERSTANDING IMMUNITY

The immune system is one of the great wonders of nature, rivalled only by the brain in its intricacy and elegance of design. It is a multi-layered system of biological defences whose primary purpose is to defend the body from bacteria, viruses, fungi, parasites, toxins, cancerous cells and other disease-causing agents. The immune system is indeed a system, in the strict sense of the word: a highly complex and co-ordinated array of interrelated, interacting elements.

Like the economy of a nation, the immune system is not located exclusively in one place. In fact, the cells of the immune system are spread out all over the body. The majority are located in those organs whose purpose often seems slightly mysterious to the layperson: the thymus (located at the base of the neck); the spleen (below and behind the stomach); the lymph nodes (clumps of tissue in the armpit, groin, behind the ears and elsewhere); the bone marrow; the tonsils; and obscure backwaters of the gut (Peyer’s patches and the appendix).

Immune cells are also to be found in the blood. These are the white blood cells (or leucocytes). Immune cells are carried in the bloodstream to locations in the body where they are needed, particularly sites of injury or infection. When an area of tissue is injured or infected an inflammatory response is triggered: the blood vessels swell up and become more permeable, thus increasing the supply of blood and immune cells to the damaged area.

There are numerous types of white blood cell, but here we are primarily concerned with the lymphocytes, which make up about a quarter of all white blood cells in humans. Lymphocytes can be subdivided into three main categories: B-lymphocytes, T-lymphocytes and natural killer cells.⁵ The latter are capable of spontaneously killing certain virus-infected or cancerous cells.

The body is protected by layer upon layer of immune defences, rather like the proverbial onion. Simple accounts of the immune system (and this is a very simple account) usually divide its actions into two categories: the very clever and the mind-bogglingly clever; or, more conventionally, non-specific immune responses and specific immune responses.

Non-specific immune responses are the body’s first line of defence against bacteria, parasites and other foreign material. Their basic purpose is to prevent potentially harmful foreign materials from entering the body in the first place, or to destroy them when they do enter. They achieve this without recognizing precisely which foreign material they are dealing with.

At the simplest level, non-specific defences include the physical barrier of the skin; the minute hairs called cilia in the respiratory tract and elsewhere which expel foreign particles from the body; and chemical defences such as stomach acid and bacteria-destroying enzymes in saliva and tears. A more sophisticated layer of non-specific immune defence is provided by various classes of white blood cells, notably the monocytes and neutrophils. These can ingest and destroy bacteria and foreign particles, a process known as phagocytosis (literally ‘cell-eating’). They also help other white blood cells to kill microorganisms, and produce vital chemical messenger molecules called cytokines which co-ordinate different aspects of the immune response.

Now we come to the mind-bogglingly clever part of the immune system: the part that can recognize and respond specifically to each and every type of foreign material it encounters. This is the specific (or acquired) immune response. It has the ability to make ultra-fine distinctions between material that forms part of your body and material of foreign origin – in other words, between ‘self’ and ‘non-self’. This can be achieved because the immune system contains within it a detailed image of your body. Anything that deviates from this image, including some cancer cells, is recognized as foreign and attacked. A foreign substance that generates a specific immune reaction when it encounters the immune system is referred to as an antigen (short for antibody generator).

The ability to distinguish reliably between ‘self’ and ‘non-self’ allows the immune system to attack foreign material without harming your body’s own healthy cells. Your immune system could detect the difference between a cell from your body and an apparently identical cell from my body. This is why transplanting tissue from one person to another can be such a tricky business, requiring the use of immune-suppressive drugs. In order to circumvent the immune response certain parasites have evolved the ploy of disguising themselves as the host’s own tissue, tricking the host’s immune system into regarding them as ‘self’ rather than ‘non-self’.

It is helpful to subdivide the specific immune response into two main categories: humoral (or antibody-mediated) immunity; and cell-mediated immunity. Humoral immunity is concerned with attacking antigens that are floating around in the body fluids surrounding your cells as opposed to antigens inside the cells – hence ‘humoral’ from the old word ‘humour’, meaning bodily fluid. Humoral immunity essentially involves the production of antibodies by B-lymphocytes.

Antibodies are a type of protein molecule called the immunoglobulins.⁶ They are the body’s mainstay against bacterial infection. Each antibody is unique to one particular antigen, so there are as many types of antibody as there are antigens. When a B-lymphocyte meets the particular antigen to which it responds, it undergoes biochemical changes and starts producing multiple copies of itself, a process known as proliferation. The newly formed cells that result from this proliferation, called plasma cells, then secrete antibodies into the blood. These antibodies latch on to the antigen and, all being well, the antibody-antigen complex is then chomped up by a passing phagocyte.

Cell-mediated immunity, the other main variety of specific immune response, is primarily concerned with attacking antigens inside the cells – for example, viruses. It is also responsible for the body’s immune reactions to transplanted tissues and tumours. Its main agents are the T-lymphocytes, which can recognize and kill target cells, such as those infected with viruses and foreign cells. Unlike antibodies, however, T-lymphocytes are unable to attack antigens that are floating around by themselves; instead they are dependent on other immune cells which ‘present’ the antigen to them, while at the same time stimulating the T-lymphocytes to attack by releasing chemical messenger substances known as cytokines. When stimulated in this way, T-lymphocytes proliferate and transform themselves into various subclasses with specific functions. Cytotoxic T-cells attack the antigen, while suppressor T-cells and helper T-cells regulate the whole delicate process. They do this by producing cytokines which alter the activity of other immune cells. Helper T-cells also stimulate B-lymphocytes to produce antibodies. The biological mechanisms regulating all of this are immensely complex.

The immune system learns and adapts each time it encounters a new antigen, setting a pattern for the way it will respond should it meet that antigen again. This is why you can be immunized against certain diseases, such as polio, typhoid, tetanus, rabies, diphtheria and chickenpox, and why there are diseases you catch only once in a lifetime. In this respect the immune system is like the brain: it detects and responds to specific stimuli in the outside world and then forms a long-lasting memory of those stimuli.

Vaccination exploits these immunological memory processes. A harmless fragment or heat-killed version of the bacteria or viruses is injected into the body. The antigens in the vaccine trigger the production of antibodies, but not the disease. The immune system is thus better prepared when it encounters the genuine item. Some micro-organisms are able to keep changing their biochemical appearance, which prevents the immune system from learning about them. The viruses responsible for the common cold and influenza are particularly good at this trick, which is why we do not develop permanent immunity to colds and ’flu.

Many things can impair the effectiveness of the immune system, including genetic defects, drugs and disease. There is also a general decline in immune function with old age. Sleep deprivation and poor nutrition both have marked effects on the immune system, too. Experiments on volunteers have ascertained that two or three days of sleep deprivation will produce significant reductions in various aspects of immune function. Even modest disturbances in sleep patterns can bring about measurable changes in the immune system. A study of healthy male volunteers found that depriving men of sleep for a few hours between 3 a.m. and 7 a.m. was enough to lower the immunological activity of their natural killer cells by more than a quarter. A good night’s sleep returned it to normal.

What happens when the immune system goes wrong? Although it is vital to our existence, most people have only a vague understanding of what the immune system does and seldom give it a thought until it malfunctions. If it fails to recognize and destroy potentially harmful agents such as bacteria, viruses or cancer cells the result may be a serious disease. Those born with defects in their humoral immune responses suffer from recurrent, severe infections.

AIDS is a vivid example of what happens when the immune system is damaged. The human immunodeficiency virus (HIV) wreaks its havoc mainly by destroying the victim’s helper/inducer T-lymphocytes. The eventual outcome is the almost invariably fatal condition known as Acquired Immune Deficiency Syndrome, or AIDS. One of the hallmarks of AIDS is a dramatic fall in the number and activity of helper/inducer (CD4) T-lymphocytes, though HIV does affect the immune system in other ways as well. An individual whose immune system is crippled by HIV becomes easy prey for a range of opportunistic infections and tumours, such as pneumonia, tuberculosis, Kaposi’s sarcoma and non-Hodgkin’s lymphoma, and it is usually one of these that kills the victim in the end.

AUTOIMMUNITY

In addition to destroying potentially harmful antigens, the immune system must be able to identify and avoid attacking its own body. Discriminating accurately between ‘self’ and ‘non-self’ is a fundamental requirement. There are times, however, when this discrimination fails for some reason and the immune system starts attacking ‘self’. B-lymphocytes manufacture antibodies against other cells in the body and these autoantibodies start to attack healthy tissue. The result is an autoimmune disorder. Those who liken the immune system to an army repelling foreign invaders have used the illuminating metaphor of ‘friendly fire’ to describe the phenomenon of autoimmunity.

Autoimmunity is thought to play a role in at least twenty (and perhaps in excess of forty) diseases, and the list is growing. Among those included are rheumatoid arthritis; various thyroid disorders such as Graves’s disease and Hashimoto’s disease; primary biliary cirrhosis of the liver; systemic lupus erythematosus; Guillain-Barré syndrome; multiple sclerosis; diabetes mellitus; uveitis; pernicious anaemia; myasthenia gravis; and inflammatory bowel disorders such as celiac disease, ulcerative colitis and Crohn’s disease.

The mechanisms of autoimmunity are not fully understood. Certain autoimmune diseases appear to arise because cells become altered in various ways – perhaps by viral infection or mutation – so that the immune system no longer recognizes them as ‘self’. In other cases, autoimmunity results from a failure in the complex and delicately balanced mechanisms that regulate the immune system.

Genetic factors are known to play an important role in some autoimmune disorders. For example, insulin-dependent diabetes mellitus (otherwise known as childhood-onset diabetes) results from the autoimmune destruction of cells in the pancreas, the organ responsible for producing the blood sugar-regulating hormone insulin. Diabetics have a genetic predisposition to develop the disease. But environmental factors, including stress, also play their part in determining whether a genetically predisposed individual actually develops the disease. Even if one of a pair of genetically identical twins has diabetes there is still a 50–70 per cent chance that the other twin will not get the disease. Chronic psychological stress significantly increases the risk that those who are genetically predisposed will advance to full-blown diabetes.

Females are much more susceptible than males to a number of autoimmune diseases, and this is true both in humans and other species. Women are three times more likely than men to suffer rheumatoid arthritis, six times more likely to develop autoimmune thyroiditis, and at least ten times more likely to suffer from systemic lupus erythematosus. This sex difference in disease susceptibility is at least partly a consequence of hormonal differences; male and female sex hormones, such as testosterone, progesterone and oestradiol, influence the immune system in various ways.

Autoimmune diseases result from excessive or inappropriate immune activity. Accordingly, they may be ameliorated by drugs that suppress the immune system – the opposite of what happens in normal infectious diseases. This is why doctors use immune-suppressive drugs to treat autoimmune diseases.

MEASURING IMMUNITY

A prerequisite for any research into the relationships between mind, immunity and health is the ability to measure how well (or how badly) the immune system is doing its job. But as we know all too well, the immune system is not a simple entity whose activity can be readily described by a single index, any more than the multifaceted complexities of human intelligence can be fully encapsulated in a single number called IQ. So how do scientists measure immunity?

The functioning of a highly complex system such as a national economy can be quantified, albeit rather crudely, but only by using a diverse range of measures to describe various aspects of the system. Thus economists have come up with a variety of indices for quantifying economic activity, including the gross domestic product and gross national product; the headline and underlying rates of inflation; assorted interest rates; indices of money supply; the trade balance between imports and exports; exchange rates against foreign currencies; various measures of unemployment (most of them controversial); foreign debt; government borrowing; gold and currency reserves; measures of consumer spending, and so on. Each measure says something different about the economy and no single one gives a complete picture of the whole system.

Your immune system is far more complex than any national economy. Therefore if it is simplistic to talk of a national economy going up or down, it is even more simplistic to talk of an immune system going up or down. Fortunately immunologists, like economists, have at their disposal a number of informative ways of assessing certain basic aspects of this complex system.

Much of the research on how psychological and emotional factors affect immune function has focused on the white blood cells, primarily because they are the easiest to get at. Studying what is going on inside the thymus or spleen is difficult and intrusive, but taking a blood sample is quick and painless. Modern techniques also allow scientists to measure antibodies in saliva, one of the most readily accessible bodily fluids.

Scientists assess the immune function of white blood cells in two basic ways: by counting particular types of cells to see how many there are circulating in the bloodstream, or by measuring how well those cells perform their immunological functions.

The simplest approach is to count the total number of white blood cells in a given volume of blood, although this produces a crude index of limited use. An improvement on this is to count a specific type of white blood cell, such as T-lymphocytes or natural killer cells, or to gauge the amount of a particular class of antibody. But the biological and medical meaning of these measures is not always clear. A drop in the number of circulating lymphocytes may simply mean that lymphocytes have been shunted elsewhere in the body, probably into the spleen. At any one time only about 10 per cent of all lymphocytes are circulating in the bloodstream; the rest are stored in lymphoid organs such as the spleen and lymph nodes. Further information is provided by calculating the relative proportions of various cells, such as the ratio of helper T-cells to suppressor T-cells, since these proportions must be about right for the immune system to function properly.

The second, more revealing, approach relies on what are known as functional measures. These assess how well the various cells are performing their immunological functions. Research into the relationships between psychological factors and immunity has tended to rely on two particular functional measures of immune activity: the responsiveness of lymphocytes to stimulation and the cell-killing activity of natural killer cells. Because these two measures are so central to research in this field they warrant closer inspection.

As we have already seen, lymphocytes will respond to antigens by proliferating or producing multiple copies of themselves. This response can also be triggered in a non-specific way (that is, in the absence of the specific antigen) by chemicals known as mitogens. Lymphocyte function can thus be measured in a test tube simply by introducing mitogens to the sample.⁷ Responsive lymphocytes will proliferate wildly when stimulated with the appropriate mitogen (a Good Thing), while unresponsive lymphocytes will be sluggish (a Bad Thing). Assume this is what I mean when henceforth I refer to lymphocyte responsiveness.

The prime function of natural killer cells is to destroy certain types of virus-infected cells and cancer cells. The obvious method of assessment in this case is to see how effective they are at destroying suitable target cells in the test tube. This is what is meant by natural killer cell activity, the second workhorse measure of immune function that will crop up repeatedly in subsequent chapters.⁸

It has to be admitted that lymphocyte responsiveness, natural killer cell activity and most of the other measures commonly used to assess immune function are flawed, allowing only a partial glimpse into the complexities of the immune system. Scientists can no more encapsulate the state of an individual’s immune system in a few numbers than they can sum up that person’s behaviour or emotional state with a few numbers.

It is a curious and regrettable fact that scientists tend to place greater faith in measurements of reassuringly physical entities, like the responsiveness of lymphocytes or the activity of natural killer cells, than they do in measurements of supposedly abstract entities like thoughts, emotions or behaviour. There is no rational basis for this prejudice, which is yet another reflection of our propensity to regard mind and body as two fundamentally different sorts of thing.

Despite their appearance of objectivity and precision, immunological measures are not totally reliable and, to a degree, depend upon subjective judgements. Conversely, the common prejudice that all psychological measures are by definition subjective, unreliable and woolly is a gross fallacy. Some are, but others are not. Experimental psychologists and behavioural biologists have been devising valid, reliable ways of measuring behaviour, psychological states and emotions for over half a century.⁹ Psychological measures are not always perfect, but they are inherently no better or worse than immunological measures in terms of their reliability, validity and objectivity. (Here endeth the lesson.)

The mind – immunity connections

Scientists and doctors have traditionally tended to regard the immune system as an autonomous entity that operates to a large degree independently of the mind and behaviour; an exquisite piece of biological machinery honed by millions of years of evolution to act autonomously in protecting the body from anything the outside world can throw at it. But this view is now known to be fundamentally wrong.

The body’s three main regulatory systems – the central nervous system (which includes the brain), the endocrine system (which produces hormones) and the immune system – do not work in isolation from one another. On the contrary, they are intimately connected and interact with each other in many important ways. Events occurring in the brain can produce changes within the endocrine and immune systems through a variety of routes, including specialized nerve pathways and chemical messengers. The effect may be to impair or enhance aspects of immune function, with potential consequences for health. The central nervous system, immune system and endocrine system are part of an integrated regulatory network that helps to ensure the survival and effective functioning of the whole organism. We are not just a bag of bits.

Another common misconception is that organisms work in a top-down, hierarchical manner with commands flowing in a single direction, from the brain to the rest of the body. In reality, information flows both ways along the various biological pathways that connect the central nervous system, endocrine system and immune system. Activity within the immune system can therefore influence the brain, mental state and behaviour.

Some scientists have likened the immune system to a sort of sensory organ, which is distributed throughout the body and provides the brain and endocrine system with information about the internal and external environment. This analogy makes good biological sense. The immune system detects the presence of antigens, including cells of its own body which have undergone change. It then transmits this information to the central nervous system, together with information about its immune response.

The new field of scientific research which is concerned with the complex inter-relationships between psychological and emotional factors, the brain, hormones, immunity and disease goes by the jaw-bending name of psychoneuroimmunology. In the next chapter we shall examine a few examples of how the brain and immune system interact. Before we do that, however, let us glance at the nature of the mechanisms which connect the brain and the immune system.

Since the 1980s, psychoneuroimmunologists have made considerable progress in understanding the biological pathways by which the brain and immune system influence each other. These pathways are of two basic sorts: electrical pathways using nerve connections, and chemical pathways using hormones, neuropeptides and other chemical messenger molecules. The specialized nature of these mechanisms strongly implies that they have evolved for a purpose – to enable the brain and the immune system to communicate with each other.

One good reason for believing that the brain and the immune system are meant to communicate is that they are hard-wired to each other by nerve connections. The tissues of the immune system are connected to the central nervous system by a rich supply of nerves. These nerve connections are responsible, amongst other things, for helping to regulate the development, activity and movement of lymphocytes and other immune cells.

Immune tissues in the spleen, bone marrow, thymus, lymph nodes, tonsils and gut are all abundantly supplied with nerve endings. Bone marrow, for example, is connected to the central nervous system by nerves emanating from the spinal nerve which supplies that region of the body. Some of the nerve connections in immune tissues do have other purposes, such as helping to regulate the local flow of blood, but some nerves undoubtedly pass information between the immune tissues and the brain. The spleen has a dense network of nerve connections and at least half of them are involved in transmitting information to and from the brain.

The second principal way in which the brain and immune system communicate is through an array of special chemical messenger molecules. The central nervous system and the immune system – the body’s two great regulatory and memory systems – have a lot of chemical communications hardware (or should I say wetware) in common. That such vast numbers of these chemical messengers have been discovered indicates their importance as a mechanism of communication between the central nervous system and the immune system, and also within each system.

Neurotransmitters, hormones and other chemical messenger molecules that were once thought to be restricted to the brain and nervous system are now known to be active within the immune system as well. Conversely, certain immunotransmitters and other chemical messengers that were once thought to be exclusive to the immune system are now known to act on the endocrine and central nervous systems. The brain and the immune system speak the same languages.

Cells of the immune system have special biochemical receptor sites on their surfaces which respond specifically to chemical messengers produced by the central nervous system. Lymphocytes and other immune cells respond to a range of neuropeptides, neurotransmitters and hormones which are either produced directly by the central nervous system, or whose secretion is under its control. These chemical messengers include noradrenaline, corticosteroid hormones, endorphins, encephalins, growth hormone, adrenocorticotrophic hormone (ACTH), prolactin, substance P, substance K, vasoactive intestinal peptide (VIP), angiotensin and somatostatin. A number of these chemical messengers travel to the immune system via the blood circulation; others, like neuropeptides, are also delivered locally from nerve endings.

These chemical messengers are able to modulate aspects of cell-mediated and antibody-mediated immunity. For example, the hormone noradrenaline, which is released from the adrenal glands (under stimulation from the brain) and from nerve endings, has widespread effects on immune function. Noradrenaline can facilitate the production of antibodies in various immune tissues; it can also inhibit the division of lymphocytes and impede the destruction of virus-infected cells or cancer cells by the immune system. Another messenger molecule, substance P, makes lymphocytes more responsive to stimulation, increases the production of certain types of antibody and facilitates the movement of lymphocytes to sites of infection.

We shall see in chapter 5 how psychological stress stimulates the release of hormones, including cortisol, a steroid hormone which suppresses various aspects of immune activity. The stress-induced release of cortisol is controlled by a region of the brain called the hypothalamus. The hormone prolactin is also released in response to psychological stress; unlike cortisol, however, its main effect on immune activity is stimulative.

Chemical communication between the central nervous system and immune system also works both ways. The immune system sends chemical messages to the brain. Immune cells produce neuropeptides, hormones and other chemical messengers, including ACTH, endorphins, encephalins, VIP and growth hormone, which influence both the endocrine and central nervous systems.

Some of the most important messenger molecules mediating the communication between the central nervous system and immune system are the cytokines. These were originally thought to be exclusive to the immune system, but they are now known to act on the central nervous system and endocrine system as well. Scientists have found that cells in several regions of the brain and central nervous system either contain cytokines or have receptor sites for them. When cytokines are released by activated immune cells they can have widespread effects on an organism’s nerves, hormone levels and psychological state. For example, when an infection occurs the cytokine interleukin-1 (IL-1) acts on the brain to induce slow-wave sleep and loss of appetite; IL-1, acting in concert with interleukin-6 (IL-6), induces fever by modulating the temperature control centres in the brain – in effect, putting the body’s thermostat on a higher setting. IL-1 and IL-6 help to make you feel hot, sleepy and indifferent to hunger when you are ill. Cytokines are also active within the endocrine system. The cytokines IL-1, IL-2, IL-6, interferon-gamma and tumour necrosis factor (TNF) are all capable of influencing the release of hormones by the pituitary and adrenal glands.

Small changes to the structure of the brain will produce corresponding changes within the immune system, thus providing further evidence of communication between the two. Highly localized damage (or lesions) to parts of the brain, including the limbic forebrain, hypothalamus, brain stem and cerebral cortex, can bring about specific changes in immune function. Small lesions in the anterior hypothalamus produce reductions in lymphocyte responsiveness, natural killer cell activity and antibody production, while lesions in limbic forebrain structures such as the hippocampus and amygdala can increase the responsiveness of T-lymphocytes. Brain lesions can even modify certain immune-mediated diseases. For example, tiny lesions in the anterior hypothalamus alter the growth of tumours and allergic responses. In addition, animals with certain hereditary defects in their central nervous system are more vulnerable to immunologically-mediated disorders such as arthritis.

A final and fundamental point, to which we shall be returning in subsequent chapters, is that the electrical and chemical communication pathways between the central nervous system and the immune system operate in both directions. Information about the state of the immune system can be passed up to the brain and hence influence the organism’s psychological state.

There is abundant experimental evidence that changes in immune activity are accompanied by corresponding changes in hormone levels, nerve activity and psychological state. Experiments have further revealed that patterns of electrical and chemical activity in the hypothalamus, limbic forebrain and other brain regions are linked to changes in immune activity which occur during the course of an immune response. For example, the peak production of antibodies in reaction to an immunological challenge (inoculation) is accompanied by changes in the electrical activity of nerve cells in the hypothalamus and other parts of the brain. Our brains appear to know, at least to some extent, what is going on within our immune systems.

In conclusion, then, we have seen that our psychological and emotional state can shape our perception of health and hence our sickness-related behaviour. At the extremes we may, like Colin Craven, feel ill and demand medical attention even though we have no disease; or, like Henry Earlforward, we may deny the reality of our symptoms and allow a serious disease to advance unchecked.

But our minds do far more than alter our perception of reality: they alter reality itself. The mind can affect our susceptibility to real physical diseases by modifying our behaviour or by directly influencing our immune defences, to which it is connected via electrical and chemical communications pathways.

By means of these psychological and biological mechanisms our minds really can make us ill.

4 Mind and Immunity

O the mind, mind has mountains; cliffs of fall

Frightful, sheer, no-man-fathomed. Hold them cheap

May who ne’er hung there.

Gerard Manley Hopkins, No worst, there is None (1885)

Evolution has equipped our bodies with psychological and biological mechanisms which enable the brain and immune system to talk to each other. Let us now examine what happens when these mechanisms operate in practice. In this chapter we shall look at what the immune system can do to the mind and, conversely, what the mind can do to the immune system. We shall see that changes in a person’s mental state can affect their immune function and vice versa. Then we have the remarkable phenomenon of immune conditioning, which teaches the immune system to respond to purely psychological stimuli. We shall explore the curious connections between left-handedness, developmental learning disorders and immunological diseases. To round off the story we shall study in closer detail one specific instance of how mind, body and health interact, by considering herpes virus infections.

What can the mind do to the immune system?

Let us start with the most basic of psychoneuroimmunological questions. (The question is much simpler than its epithet.) What effects do psychological factors actually have on the immune system?

Probably the first ever scientific account of a psychoneuroimmunological phenomenon appeared in 1919, when a Japanese scientist called Ishigami published the results of his research on tuberculosis in schoolchildren. Ishigami observed that an increase in tubercular illness coincided with a period when the children and their teachers were experiencing high levels of ‘emotional excitement’. Using a crude immunological measure – the ability of white blood cells to destroy foreign bacteria – Ishigami was able to relate this upsurge in disease to a decline in immune function. He concluded that the emotional stress was responsible for the decline in immunity which, in turn, led to the increased incidence of disease.

Since Ishigami’s day, and especially since the 1980s, scientists have accumulated a huge and varied pool of evidence that psychological and emotional factors influence the immune systems of humans and other species, with consequential effects on physical health.¹ It is time to look at a few examples.

BEREAVEMENT AND NUCLEAR DISASTERS

The death of a spouse or partner is one of the most devastating forms of psychological and emotional disturbance anyone can experience. It is also surprisingly common, affecting more than 800,000 people each year in the USA alone. By the age of sixty-five over 50 per cent of American women have been widowed at least once.

Bereavement considerably heightens the risks of death and disease for the surviving partner. The risks are particularly great if the surviving partner is male: widowed men in their twenties have a mortality rate seventeen times higher than comparable married men. Moreover, the increased mortality rates among widowers persist for several years after the death of their wife.

One factor in this increased disease and mortality among the bereaved may be that they undergo changes in their immune function. A number of surveys have found that the death of a spouse is followed by measurable reductions in the immune function of the surviving partner.

In a pioneering 1970s study of this phenomenon, scientists at the University of New South Wales in Australia took blood samples from recently bereaved people and measured how responsive their lymphocytes were to stimulation by mitogens. The results were compared against the immune function of non-bereaved individuals who were matched for age, sex and other relevant factors. Several weeks after the death of their spouse the bereaved subjects’ T-lymphocytes were significantly less responsive.

Similar conclusions emerged from a prospective study which investigated the immune function of men whose wives had terminal breast cancer. During the weeks immediately following bereavement the widowers’ lymphocytes were not as responsive as they had been beforehand. In the majority of cases their lymphocyte function eventually returned to normal, but some men were still exhibiting reduced immune function a year later. The changes in lymphocyte responsiveness could not simply be explained away as by-products of behavioural changes which might also have followed bereavement, such as disrupted sleep, inadequate diet or increased smoking.

Bereavement is also followed by a drop in natural killer cell activity. Scientists have found reductions in the natural killer cell activity of women whose husbands have died from lung cancer within the previous few months and in women whose husbands are in the final stages of lung cancer.

The death of a partner is obviously not the only way in which marriages or long-term relationships are disrupted. Separation and divorce also result in the severing of ties and can have an effect on the partners’ immune function and health. Indeed, the health risks arising from separation and divorce are, if anything, worse than those associated with bereavement.

The stress which attends the loss of a partner is as old as the human race, but the twentieth century has ushered in new anxieties, such as the prolonged fear of exposure to dangerous radiation following a nuclear accident. Sadly, this is now a well-documented phenomenon. One of the most detailed scientific investigations of chronic stress has been conducted on people living near the damaged Three Mile Island nuclear power plant in Pennsylvania.

On 28 March 1979 the Three Mile Island reactor suffered a serious accident. Fortunately, the damage was contained and there was no significant release of radiation into the surrounding environment. However, the accident understandably generated great anxiety and distress among local inhabitants. In its immediate aftermath there was panic and confusion; saturation reporting by the media fanned the flames of fear that the reactor core would melt down and cause a massive release of radiation. Even after the initial crisis had passed, locals were painfully aware of the long-term clean-up operation and the continuing threat posed by the damaged reactor. Fear, anxiety and stress persisted for years.

Six years after the Three Mile Island incident American scientists measured the immune functions of people living within a five-mile radius of the damaged reactor. Compared with matched control subjects living further away, those living near Three Mile Island had markedly impaired immune systems. To be specific, they had fewer circulating B-lymphocytes, fewer natural killer cells, fewer suppressor/cytotoxic T-lymphocytes and a reduced immunological control over latent herpes viruses. And to round off the picture, they also showed a higher degree of anxiety and psychological distress; higher blood pressure; higher average pulse rates; and higher levels of the stress hormones adrenaline, noradrenaline and cortisol.

The Three Mile Island incident demonstrated quite clearly that, irrespective of whether or not there is a release of harmful radiation, the psychological stress which attends a nuclear accident can still have a major impact on mental and physical wellbeing. A further general conclusion from this and similar studies is that the immune system does not always adapt to long-term stress. Prolonged stress can produce a prolonged depression in immune function. It can also have some subtle effects on disease patterns.

The plot thickened. Three years after the original accident a team of researchers from Columbia University discovered an unusually high incidence of cancers among local inhabitants. In 1982 the incidence of all types of cancer among those living near the plant was 50 per cent above the historical norm. However, the cancer rate then started to fall, and by 1985 it had dropped below the long-term average. Meanwhile, cancer rates among the control subjects living further away from the plant had remained roughly constant. What was going on?

A number of fine minds were brought to bear on this problem. They concluded that subtle psychological processes lay at its root. All the evidence indicated that this peculiar blip in the cancer rates was not merely a consequence of exposure to radiation released from the damaged reactor. For a start, very little radiation had been released and the levels were too low to have caused a measurable increase in cancer. Moreover, there was no discernible association between the recorded levels of radioactivity and the pattern of cancer occurrences in the Three Mile Island area. The consensus among scientists was that the cluster of cancers around Three Mile Island could not be attributed directly to radiation.

Instead, it appeared that the transient increase in cancer rates probably stemmed from the high degree of psychological stress local residents were experiencing. Psychological surveys confirmed that the closer a subject lived to the plant, the higher on average their levels of anxiety and distress.

Psychological stress could have generated the apparent rise in cancer rates in two distinct ways. First, the local population had been bombarded with publicity about the potentially dire health consequences of the incident. They were more anxious about their health in general and particularly concerned about the dangers of radiation-induced cancer. It is therefore probable that they would have paid closer attention to their own health – especially to any possible symptoms of cancer – and would have sought medical attention at an earlier stage than individuals who were less concerned. This process would explain why cancer rates initially rose and then fell below the long-term average. The overall long-term incidence of cancer stayed roughly constant, but in the years immediately after the accident cancers were being diagnosed at an earlier stage in the disease – hence the blip.

Assuming this hypothesis is true, the Three Mile Island incident might actually have helped to save the lives of a few people who would have died had their cancer progressed undetected.

A second and more direct route by which the Three Mile Island accident could have influenced cancer rates is through stress-induced changes in immune function. The prolonged stress of worrying about the hazards posed by the damaged reactor might have led to an impairment in immune function, thus increasing locals’ susceptibility to cancer or, more plausibly, promoting the growth of existing, early-stage tumours.

The Three Mile Island incident was to prove a pale shadow of what took place seven years later in the Ukraine. The Chernobyl nuclear disaster in April 1986 resulted in vast quantities of radioactive material being released into the environment. Thousands of square miles were contaminated and the inhabitants exposed to dangerously high levels of radiation which claimed hundreds of lives. Stress contributed to the problem, making an appalling situation worse. The official scientific report produced for the United Nations International Atomic Energy Agency commented that there were very high levels of psychological stress even outside the contaminated regions.

Another nuclear accident that caused serious psychological and physical damage, albeit on a smaller scale than Chernobyl, occurred in Brazil the following year. In September 1987 an unsuspecting thief stole twenty grams of caesium-137, a highly radioactive isotope, from a disused clinic in Goiania, a town in central Brazil. Before the true nature of the theft was discovered, the strange substance which glowed in the dark had been handed around the neighbourhood. Tragically, 118 people were contaminated with caesium-137, of whom 4 died from the immediate effects of radiation. And, as at Chernobyl, the entire population of the surrounding area was confronted with the dreadful possibility that they might have been exposed.

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