Men with persistent symptoms of depression may be twice as likely to die of a stroke as well as face greater risks of heart disease compared with men with little or no depression symptoms, according to a new study.

Researchers say the study is one of the largest to look at the association between depression and heart disease and stroke. The results suggest that a dramatic increase in stroke risk may be behind the higher risk of cardiovascular-related deaths found among people with depression.

The studies so far on the issue of depression and death risk, particularly risk of death from cardiovascular disease, have been inconclusive. About half of previous studies related to risk of death and depression have found that having depression increases the risk of death, but nearly a quarter have shown the reverse, and the remainder had conflicting results.

Depression Symptoms Linked to Stroke Risk

In the study, researchers followed nearly 13,000 men from across the U.S. who participated in the Multiple Risk Factor Intervention (MRFIT) Trial. The men were an average of 46 years old at the start of the study and were considered to have an above-average risk of heart disease due to various risk factors, but none of them had evidence of heart disease.

In the sixth year of the study, the men answered a questionnaire to asses their depressive symptoms. The symptoms were rated on a four-point scale, with zero meaning they rarely experienced depressive symptoms and three meaning they experienced symptoms most of the time.

During the next 19 years, researchers tracked deaths and the cause of death among the men.

After adjusting for age, blood pressure, and other factors that may have affected the results, researchers found that men in the top one-fifth of depression scores were:

--15 percent more likely to have died of any cause

--21 percemt more likely to have died due to heart disease

--Twice as likely to have died due to stroke compared with men in the lowest fifth of depression scores

The results appear in the Nov. 29 issue of "Stroke: Journal of the American Heart Association."

Researchers say although 22 percent of these men had developed heart disease by the time they filled out the depression questionnaire, the relationship between depression and heart disease death risk was consistent regardless of the men’s history of heart disease.

Even Mild Depression May Be Risky

"Because of the size of MRFIT, we were able to look at depression as a continuous measure in our analysis, which led to another significant finding: that even mild depressive symptoms were associated with an increased risk of stroke death compared to subjects with no depressive symptoms at all," says researcher Karen A. Matthews, PhD, professor of psychiatry, psychology, and epidemiology at the University of Pittsburgh, in a news release.

However, researchers say the study did not rule out the possibility that “silent” or undetected strokes may have contributed to the increased risk of heart disease deaths associated with depressive symptoms.

"That is a real possibility because silent strokes, by definition, are not detected clinically, but might well produce depression and predict fatal stroke later because having one stroke increases the risks of having another," says researcher Brooks B. Gump, PhD, MPH, associate professor of psychology at the State University of New York at Oswego, in the release.

By Jennifer Warner, reviewed by Charlotte E. Grayson, MD

SOURCES: Brooks, B. Stroke: Journal of the American Heart Association, News release, American Heart Association.