DALLAS — Depression boosted the risk for stroke in a study of more than 4,000 elderly people followed for 10 years.
People with the highest depression scores at baseline had twice the incidence of a cerebrovascular event or transient ischemic attack during follow-up, compared with people who had no depression, Dr. Abraham A. Ariyo reported at the annual scientific sessions of the American Heart Association.
The finding that depression is a risk factor for stroke follows a prior analysis of the same group of people showing that depression boosted the risk for coronary artery disease, said Dr. Ariyo, director of HeartMasters in Dallas.
The Cardiovascular Health Study Collaborative Research Group enrolled 4,483 men and women aged 65 or older who were completely free of any clinical sign of cardiovascular disease at baseline. The study also excluded patients who were treated with an antidepressant. All participants were assessed for depression using a modified version of the Center for Epidemiologic Studies Depression Scale.
The participants were categorized into quartiles based on their scores. Those with a score of zero had no depression. The next quartile included people with a score of 1–5, followed by quartiles with scores of 6–10, 11–15, and 16 and over.
In 10.3 years of follow-up, 533 people had a stroke, and an additional 1,359 died.
In a multivariate analysis that controlled for baseline differences in age, gender, race, marital status, income, education diabetes, serum cholesterol, and activity of daily living, the incidence of stroke was related to depression scores. Compared with people who had a score of zero, those with a score of 1–5 had 19% more strokes, those with a score of 6–10 had 57% more strokes, those with a score of 11–15 had 78% more strokes, and people with a score of 16–30 had twice as many strokes. The increased stroke rates seen in patients with depression scores of six or higher were significantly different from the rate for people with no depression.
An analysis of death rates showed a similar pattern. People with scores of 6–10 had a 27% higher death rate; those with scores of 11–15 had a 73% higher mortality; and those with scores of 16 or more had 86% more deaths.
Several mechanisms may explain how depression affects stroke rates and mortality, Dr. Ariyo said. Depressed people are less physically active and engage in more unsafe behaviors, such as smoking. They also have increased levels of circulating platelets, fibrinogen, and other factors that raise thrombogenicity. In addition, depression also boosts serum levels of steroids, free fatty acids, and other factors that are proinflammatory and proatherogenic.