Stress prepares the body to fight or flee—but it can also heighten the risk of disease
SICK AND TIRED
Stress prepares the body to fight or flee—but it can also heighten the risk of disease
When Dr. Geoffrey Dawrant arrives at his west Edmonton walk-in clinic, the question of stress is never far from his mind. And more often than not, he says, it is near the top of his patients' agendas, too.
“Often you find that the real reason for coming is stress,” says Dawrant, a general practitioner who specializes in stress management. “I see people who come in and say, ‘I’ve got this cold that hasn’t gone away for a month.’ Then I ask them about stress, and they tell me about this auntie who died a few weeks ago.” To Dawrant, the notion that illness could follow the shock of a death in the family is just plain common sense. But now, that dose of intuition is increasingly backed by scientific evidence.
Although researchers are still not certain how to explain the phenomenon, a spate of recent studies has shown that such factors as exam pressure, marital problems or the death of a family member can interfere with the body’s natural defences against disease. The result: people under severe stress may be more vulnerable to infectious diseases such as colds and the flu, can take longer to recover from surgery and may even be less likely to survive some forms of cancer. “Stress doesn’t make you sick,” says Ronald Glaser, a virologist who studies the relationship between stress and immune function at Ohio State University in Columbus. “But it does increase your risk of being sick because of what it does to your immune system.”
Most people think of stress as the day-to-day irritants that can make them tense or even panicky, such as missing a bus, feeling pressure at work or arguing with a spouse. But in medical terms, stress is a series of physiological reactions that occur in response to events, says Dr. Cliff Ottaway, an immunologist who studies stress responses in his lab at the University of Toronto medical school. Stress prepares the body to fight or flee real or perceived threats. The central nervous system plays a key role by setting off a series of
biochemical reactions that release hormones designed to prepare the body to defend itself or to handle an injury. The sweaty palms, increased blood pressure and speeding heart that most people associate with stressful situations are all part of this chain of events. Once the threat is gone, another set of hormones returns the body to its normal state. But if the
threat continues over a long time, the body may eventually fall prey to the very reactions that were designed to protect it.
Scientists now believe that this chain of events can directly affect the immune system. Although short-term stress can improve immune function, chronic stress usually suppresses immunity, says Ottaway. Scientists are just beginning to chart the pathways through which the brain and the immune system communicate. But according to one commonly held theory, corticosteroids—hormones released as part of the body’s attempt to return to normal—can change the way white blood cells signal each other to attack invaders in the blood; the change in signalling may suppress immunity. The hormone adrenaline—which helps the body gear up to handle stress—also interferes with the functioning of natural killer cells, one of the body’s first lines of defence in fighting off invaders. A third possibility, currently under study at the National Institute of Mental Health (NIMH) in Bethesda, Md., is that a substance known as CRH (corticotropin releasing hormone), which acts with adrena-
line to modulate the stress response, may stick to immune cells and produce proteins that encourage viruses and cancer cells to multiply.
Whatever the mechanism, numerous studies—mostly in the United States—have
linked prolonged stress with an increased vulnerability to infectious disease. Sheldon Cohen, a psychologist at Carnegie Mellon University in Pittsburgh, showed the connection in a 1991 study of 420 British volunteers who were questioned about recent stressful events and then squirted with either a cold virus or saline solution. Not surprisingly, some 38 per cent of volunteers squirted with a virus caught a cold, compared to none of those who had a saline solution sprayed in their noses. But, says Cohen, the more stressed the subjects felt, the greater chance they had of getting sick. Of those exposed to the virus, nearly half the patients who were most stressed developed a cold, compared with 27 per cent of the least stressed subjects.
Studies at Ohio State have also shown that emotional state can influence the severity of an illness and a patient’s ability to recover. Researchers compared the immune functions of 69 people who were taking care of a spouse with Alzheimer’s disease to those of 69 people living with a healthy spouse. After a year, says study co-author
Glaser, key measures of immune function were weaker in the caregivers than in subjects who were free of the obligation. Among those who got sick, the care-givers stayed sick an average of twice as long.
Even so, most experts agree that whether stress will help to make someone sick depends on a complex group of interactions that may include genetics, how the stress is perceived and the resources available to the person under stress. In fact, studies show that short-term stress can actually improve immune function in some people. ‘The exact same set of changes may be good for one person and bad for another,” says Robert Ader, a University of Rochester psychologist credited with reviving interest in the study of stress and immunity in the mid-1970s. ‘The question is, how does this stressor at this time in this patient affect the patient?” For instance, although the death of a spouse is usually stressful, the surviving spouse may not suffer negative health effects if the marriage was abusive, Ader says. “The death of that spouse may represent a gain,” he adds. “If it is not perceived as an event which requires major adaptation or an event which is threatening to the individual, we don’t have to worry about coping.”
Genetics may also play a role in whether or not health is affected, adds Glaser. “If your genetic background translates into a particularly vigorous immune response, then your immune system may not be quite as susceptible to stress,” he says. Studies in monkeys also suggest that “uptight” mothers who react adversely to changes in their environment—a reaction characterized by a flood
of immune-suppressing cortisol into the bloodstream—can pass these characteristics on to their offspring, either through genetics or through nurturing.
Social support may be just as important in determining whether stress can influence the immune system, says Dr. David Spiegel, professor of psychiatry and behavioral sciences at California’s Stanford University School of Medicine. Research by Spiegel’s team, published in the scholarly journal The Lancet in 1989, showed that women with advanced breast cancer lived an average of 36 months if they joined a support group, compared with an average of 18 months if they did not. Some women who are most anxious have higher cortisol levels, which is a sign of stress and may suppress the immune system, in turn allowing tumors to grow more quickly. On the other hand, says Spiegel, women who feel supported may have immune systems that work better and can hold tumors at bay. “While group therapy is certainly not a cure for cancer,” he says, “it may help the body to cope.”
A better understanding of the connection between mental and physical health is paving the road for new treatments and preventive measures for stress-related disease. If scientists can identify the pathways that connect stress and the immune system, they may also be able to design new drugs that could interfere with the process, says Dr. Julio Licinio, chief of clinical research at the clinical endocrinology unit at NIMH. “You cannot just try to reduce stress for everybody,” Licinio notes. New drugs, he adds, could be used to target patients
whose health could be seriously affected by stress, such as cancer survivors who are at risk of having a relapse or who have tumors that cannot be removed through surgery or radiation.
The research also suggests that there is more to staying healthy than simply reducing stress. “Relaxation is fine, but it is not going to make the problem go away,” says Ader. Specialists recommend learning to better cope with stress—rather than trying to pursue a stress-free life. For instance, women enrolled in the Spiegel study and its Canadian counterpart, the Breast Expressive-Supportive Therapy (BEST) study, are encouraged to face their fears and to set goals. “We don’t believe that positive thinking can make you feel better,” says Dr. Pamela Goodwin, principal investigator of the BEST study and director of the Marvelle Koffler Breast Centre at Mount Sinai Hospital in Toronto. “The important thing is to move beyond the fear and to enjoy life and to develop meaning in life.”
Dawrant also recommends improving physical well-being by exercising, eating well and cutting back on tobacco and alcohol, volunteering or joining in community activities and making an extra effort to socialize. Together, those simple measures can improve emotional outlook and reduce the burden of stressful events, he says. And although there is no guarantee they will prevent a trip to the sickbed, chances are that modern stress-fighters will have more fun along the way.
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