Studies Find Stress Can Hurt Body’s Immunity
NEW YORK — Anecdotes about links between emotion and immunity are legion, from nervous teens and their cold sores to bereaved widowers suddenly beset with ill health.
Scientists have long suspected that stress can interfere with physical well-being and even increase the risk of death, but they are just beginning to discover chemical links between the neurological and immune systems that could explain the observations.
Older studies have shown, for example, that bereaved men are more likely to succumb to illness than are men in the general population. Stress, even from less dire circumstances, often seems to result in illness, such as for the anxious teen-ager who develops a cold sore just before the school prom.
“Until recently, the immune system was thought of as auto-regulated. Indeed, it is exquisitely self-regulating. But there is a compelling amount of data now that indicates that stress is linked with lowered immune system activity,†said Dr. Marvin Stein, professor of psychiatry at Mt. Sinai School of Medicine in New York.
White Cells Drop Before Exams
He cited a study of 75 medical students who showed a significant drop in the numbers of white blood cells important to the immune system during the month before final exams.
Another study of a group of men whose wives suffered fatal cases of breast cancer showed that the widowers had lowered immune system activity, which appeared related to the anxiety and depression they were suffering at the time.
It is known that the hypothalamus, the part of the brain that controls the autonomic nervous system, and the hormonal system can moderate immunity. And immune system cells, called lymphocytes, have surface receptors where hormones and chemicals from the brain can attach and affect immune functions.
Other studies have located nerves that connect directly to immune tissue, feeding back to the central nervous system.
“They are intimately related to one another,†Stein said of the immune system and the brain. “So it makes good sense that behavioral states influence immunity.â€
Although studies have found that the body apparently cannot adapt to unmitigated stress, it can restore its immune system when stress is relieved, suggesting treatments like psychotherapy could improve response to disease.
There is no proof that positive thinking translates into improved health, although there are claims that some cancer and AIDS patients have benefited from experimental therapies like relaxation and positive imaging.
Dr. Nicholas Hall, a microbiologist at George Washington University, said he remains skeptical of such claims even though he plans to continue studying the issue and will this year become director of the Psychoimmunology Laboratory at the University of South Florida Psychiatry Center.
Warning against jumping to conclusions about emotions and health, he noted that it is possible that in response to disease, the immune system itself might trigger the release of hormones, such as interleukin I and thymosins, which can affect mental states.
Don’t Blame the Patient
Stein also cautioned against interpretations of the current data that might blame the patient for illness, or conclude that a stressed immune system always leads to disease.
“Suppression of the immune system following stress is one observation. The fact that stress is linked to increased morbidity and disease is another, separate observation. There is a tendency to put the two together. . . . But there is no evidence to support that,†he said.
