For decades, investigators have been looking at psychological factors that might increase the risk of heart disease, according to Reiner Rugulies, Ph.D., of the University of California, San Francisco. The results, including numerous findings on "so-called type A behavior" and risk of heart disease, have been largely inconsistent, he said.

However, Rugulies said research on depression and heart disease provides a far more consistent picture, indicating that "depression is associated with the development of [heart disease] in initially healthy people."

Rugulies said he examined 11 large-scale studies on depression and future heart disease published between 1993 and 2000. In each study, the investigators categorized each participantas depressed or not depressed, then followed them for anywhere between three and 37 years to document heart attacks and deaths from heart disease. The researchers assessed and tracked more than 36,000 men and women, most of whom were Americans, according to the study.

"Depression was associated with a significant increased risk of [heart disease] in seven of the 11 studies, despite the subjects’ initial good health," Rugulies said.

The depressed individuals were between one and four times more likely than their non-depressed counterparts to develop heart disease; the remaining four studies also support a depression-heart disease link, although the evidence they provide is weaker, according to Rugulies.

The most striking association appeared in those studies in which subjects were required to suffer from clinical depression, not merely depressed mood, in order to be counted as "depressed," Rugulies reported. On the average, subjects with clinical depression were almost twice as likely as individuals with depressed mood and almost three times as likely as non-depressed individuals to develop heart disease, he added.

Exactly why depression precedes heart disease isn’t clear, Rugulies noted.

"Some insight may be gleaned from research that has...shown that depressed subjects have a higher risk of hypertension and are more likely to show poor health behaviors, such as smoking and lack of leisure-time physical activity," he said. "The ability to find the answer will depend on research that integrates social, psychological and biomedical aspects in a broader framework."

Copyright 2002 Health Resources Publishing