Oct. 10, 2000 DALLAS, Oct. 10, 2000 - Some of the strongest evidence so far suggests that people who commonly experience symptoms of depression are more likely to develop heart disease, according to an article in today's Circulation: Journal of the American Heart Association.
In a multicenter, six-year study of people age 65 or over who were initially free of heart disease, researchers found that those who reported feeling symptoms of depression most often were 40 percent more likely to develop heart disease than those who reported feeling depressed the least often. "This study has established that symptoms of depression are an independent risk factor for coronary heart disease in older individuals," says Curt Furberg, M.D., Ph.D., a professor of public health science at Wake Forest University, Winston-Salem, NC. "This doesn't mean that depressive symptoms are a cause of coronary heart disease but that the presence of depressive symptoms predicts the development of disease."
Depression in the elderly is a common but often untreated condition that increases the risk of coronary heart disease and death in this age group. Depressive symptoms, which include feelings of fear or loneliness, irritability, lack of concentration, and sleeplessness, occur in 19 to 30 percent of people age 65 years or older - about 5 million Americans. Yet only one percent of those affected receive treatment, according to the study authors writing for the Cardiovascular Health Study Collaborative Research Group.
Researchers followed 4,493 elderly participants who were free of cardiovascular disease at the beginning of the study and assessed their depressive status annually with the Depression Scale of the Center for Epidemiological Studies. The Depression Scale is a 10-item scale where, for each item, participants are asked to indicate the number from zero to three that best describes how often they felt or behaved a certain way within a week. A zero indicates "rarely or none of the time" and a three indicates "most of the time." The scores can range from 0-30. Traditionally, a score greater than 8 is recognized as "at risk for clinical depression," says Furberg. Most cumulative depression scores for participants in the study ranged from 6-8.
Participants were given a 90-minute home interview and asked questions regarding their health, medications, feelings of depression, irritability, worry, fear, and loneliness, and whether they have trouble focusing on daily activities. Participants also underwent medical exams.
"Those with higher scores reported that they felt 'down,' didn't sleep well, were unhappy or had little hope about the future," notes Furberg. "These are the typical symptoms of depression that many people have at times."
The researchers found that women reported more depressive symptoms than men. Married participants or those who lived with others had lower depression scores. Smokers and those who had problems performing daily activities due to physical impairment had higher scores. Participants who were inactive and overweight also had higher scores.
Every 5-unit increase in the average depression score was associated with a 15 percent increased risk of developing coronary heart disease. A 5-unit increase in the depression score also resulted in a 16 percent increase in death after adjustment for other risk factors.
Because the study excluded people with prior heart attack or cardiovascular disease and those who were in a medical or retirement facility, Furberg says it is unlikely that the depressive symptoms occurred as a result of disease.
Furberg says there are three plausible explanations for why depression might predispose some individuals to increased heart risk: Depression is associated with poor physical activity, less exercise, more smoking and an increase in other behaviors that increase heart disease risk. A depressed state also increases mental stress, which may increase plaque formation and vessel blockages. And, thirdly, depression is thought to increase production of free radicals and fatty acids, which can damage the lining of blood vessels placing the person at higher risk for sudden death, Furberg says. It remains unknown whether treating depression in the elderly will reduce the rate of heart disease and death.
"We have shown an association, but the next step is whether treatment will stave off or slow the progression of heart disease," he says. Two clinical studies involving the treatment of depression in elderly Americans are being undertaken.
The study was supported by the National Heart, Lung, and Blood Institute. Other researchers include Abraham A. Ariyo, M.D., M.P.H.; Mary Haan, M.P.H, Ph.D.; Catherine M. Tangen, Ph.D.; John C. Rutledge, M.D.; Mary Cushman, M.D., M.S.; and Adrian Dobs, M.D., M.H.S.; for the Cardiovascular Health Study Collaborative Research Group.
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