The medical community has been slow in acknowledging the role of stress in illness. In part this is due to the general physical orientation of the medical profession: physical ailments are produced by physical causes and should be treated with physical intervention. What has been missing from the studies to make them more acceptable to the medical community is the identification of a specific physiological mechanism by which emotional states contribute to the onset of illness. The delineation of just such a mechanism is emerging from recent research on the effects of chronic stress. To understand the findings', you may find it helpful to know a little more about the physiology of stress.
The human nervous system is the product of millions of years of evolution. For most of human existence the demands placed on the nervous system were very different from those placed on us by modern civilization. Survival in primitive societies required that humans be capable of immediately identifying a threat and making a quick decision whether to fight or flee. The nervous system is an external threat, our bodies are instantly primed (via a change in hormonal balances and never outputs) either to fight or flee.
But life in modern society requires that we frequently inhibit our flight-or-flee responses. When a policeman stops you to give you a speeding ticket or when your boss berates your performance, your body is instinctively mobilized by the threat. In these circumstances, however, either "fighting" or "fleeing" would be a socially inappropriate response, so you learn to override your reaction. Throughout the day, you constantly override your body's responses to stress—when a mistake is made, a taxi honks too loudly, you have to wait in lines, you miss a bus, and so on.
The body is designed so that moments of stress, followed by a physical reaction such as fighting or fleeing, do little harm. However, when the physiological response to stress is not discharged—because of the social consequences of "fighting" or "fleeing"—then there is a negative cumulative effect on the body. This is chronic stress, stress that is held in the body and not released. And chronic stress, it is increasingly recognized, plays a significant role in many illnesses.
Dr. Hans Selye, mentioned previously, an endocrinologist and director of the Institute of Experimental Medicine and Surgery at the University of Montreal, described the effects of chronic stress on the body. His description reads like a list of medical horrors.
To start with, chronic stress frequently produces hormonal imbalances. Since hormones play a critical role in regulating body functions, these imbalances can lead to high blood pressure and eventually damage to the kidneys. The damage to the kidneys can, in turn, lead to severe hypertension (high blood pressure), which will reinforce the chemical imbalance.
In addition, the hormonal changes resulting from stress can allow tears to develop in the walls of arteries. The body repairs these tears by a buildup of cholesterol plaques, a type of scar tissue. But too many plaques cause hardening of the arteries, arteriosclerosis. This, in turn, forces the heart to pump harder to circulate the blood, further increasing the blood pressure. When arteriosclerosis becomes far advanced, it diminishes the amount of blood and oxygen reaching the heart to the point that coronary failure may occur. The cholesterol plaques may also block the heart's major coronary arteries, causing part of the heart muscle to die, resulting in eventual heart failure. Normally, the body will make an effort to adjust to these problems, but under chronic stress the mechanisms responsible for reducing and adjusting hormonal imbalance are overriden. The imbalance just continues in an increasingly negative and life-threatening cycle.
This evidence clearly demonstrates the very real physical effects of stress. But it is still another effect that is of greatest importance to the cancer patient. Selye has discovered that chronic stress suppresses the immune system which is responsible for engulfing and destroying cancerous cells or alien microorganisms. The important point is this: The physical conditions Selye describes as being produced by stress are virtually identical to those under which an abnormal cell could reproduce and spread into a dangerous cancer. Not surprisingly, cancer patients frequently have weakened immune systems.
Selye's findings are confirmed by other researchers. Dr. R. W. Bathrop and his associates at the University of New South Wales, Australia, have conducted studies indicating that bereavement lowers the body's immune response. They tested twenty-six recently bereaved persons (ages twenty-five to sixty-five) at two weeks and six weeks after their spouses' death. A control group was established of twenty-six hospital employees who had not experienced any bereavement in the past two years. Lymphocyte function, a critical measure of the potency of the body's immune system, was significantly depressed in those who had lost a wife or husband. Since the immune system serves as a potent defense against the reproduction of cancerous cells, as we discussed in the last chapter, evidence that emotional loss can lead to a suppression of the immune system is an important clue to the causes of cancer.
Another study that points to mental factors leading to the suppression of the immune system was conducted by Dr. J. H. Humphrey and his associates at the British Medical Research Council. Their research demonstrates that the body's immunity to tuberculosis can be profoundly affected by hypnotic suggestion—clearly demonstrating the influence of mental and emotional stress on the body's defenses.
Finally, Dr. George Solomon of California State University has discovered that incisions in the hypothalamus—a portion of the brain that significantly affects endocrine production in the body—lead to a suppression of the immune system. The hypothalamus is also the portion of the brain considered most directly associated with emotions—another significant piece of evidence for those of us in cancer research seeking the causes of disease.
Dr. Solomon's work begins to specify the physiological mechanism by which stress could lead to a suppression of the immune system. When his work is combined with that of Selye and others, a picture begins to emerge of how emotional stress can create the conditions under which cancer can occur. What remains is the need for a sufficient understanding of the body to describe the precise links between cancer and stress.