The Sickening Mind: Brain, Behaviour, Immunity and Disease. Paul Martin

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СКАЧАТЬ 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 СКАЧАТЬ