Can Stress Make You Sick?

Research on the relationship between health and emotion indicates that stress affects the body at the cellular level in ways than increase risk of disease. Stress is linked to heart disease and hypertension and may play a role in cancer. The hypothesis that stress alters the immune function is controversial and has not yet been proven. Maintaining social relationships is an effective way to relieve stress.

Researchers who study stress and health suspect that many ills are linked to problems with the body's "fight or flight" reaction.

Many people may recall reading newspaper accounts last year of a study which found that people with a wide variety of social ties were much less likely to catch colds than those who had limited contacts with friends, relatives, neighbors, and business associates.

The investigation, which was published in June 1997 in the Journal of the American Medical Association, revealed that a lack of diverse social contacts was a stronger risk factor for colds than smoking, low vitamin C intake, or elevated stress hormones.

The Carnegie Mellon University researchers who conducted the study say that interacting with a broad array of individuals likely tempers a person's physical response to stressful situations. Although it remains unproven, the investigators suspect that social support may somehow boost immune function.

The idea that emotions are tied to health is not a new one. Before Hippocrates (500 B.C.) and until contemporary times, doctors believed that "the passions" played a role in causing disease. Modern scientists have had little reason to revisit this antiquated notion -- until recently. As they have gained a greater understanding of the way the body functions at the cellular level, they have made the surprising discovery that certain molecules transmit signals between the nervous and immune systems.

Meanwhile, animal studies have demonstrated that impairing communication between the two systems -- either by genetic engineering or with drugs -- is associated with a susceptibility to inflammatory diseases, thyroid problems, and arthritis. Such research may one day explain why there are so many variations in people's vulnerability to infections, autoimmune disorders, and even cancer.

Most human research on stress and health has looked at the link between emotions, hypertension, and heart disease. A growing and convincing body of data suggest that chronic anger, anxiety, loneliness, or depression can be lethal to people with coronary artery disease. There is also some evidence that physically healthy people who experience frequent blow-ups, who are chronically depressed, or who are constantly anxious may be setting the stage for future heart disease.

Researchers point to the fact that some heart attacks are triggered by the sudden clumping together of blood platelets -- one of the body's reactions to the evolutionary "fight or flight" response -- which is evoked by fear or anger. When these emotions run high, platelets become stickier as the body prepares itself to stanch a potential wound.

Investigators who study the effects of stress on health believe that heart disease is only one of many ills that may ultimately be linked to disturbances of the fight or flight reaction.

An Ongoing Struggle

Everyone experiences stress in one form or another. There is the acute stress of a traumatic event, such as the death or illness of a loved one or the loss of a job, or the day-to-day wear and tear from sitting in traffic jams, feeling angry or isolated, or constantly worrying about work, finances, or relationships.

When the brain perceives stress -- either from an internal or external trigger -- the fight or flight response kicks in. Initially, this reaction stimulates the release of two stress hormones: adrenalin, which is produced by the adrenal glands near the kidneys, and corticotrophin-releasing hormone (CRH), from nerve cells in the hypothalamus, at the base of the brain. CRH then travels to the pituitary gland, where it causes the release of adrenocorticotrophic hormone (ACTH); this triggers the production of cortisol by the adrenal gland.

In response, blood platelets aggregate, immune cells activate, blood sugar rushes to muscles to give them energy, the heart and breathing rate quickens, and blood pressure rises. Cortisol, a steroid hormone which at first sustains the stress response, later slows it down so the body can return to normal functioning. Sometimes, however, this feedback loop goes awry. If stress hormones fail to turn off once the challenge has passed or if a person is subjected to chronic stress, cortisol and other hormones can get out of whack. Instead of providing protection, they may suppress the immune system by interfering with the regular repair and maintenance functions of the body, leaving people open to infections and disease.

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