Читать книгу The Sickening Mind: Brain, Behaviour, Immunity and Disease - Paul Martin - Страница 8

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.