Sadness, Heart Disease Are Linked. But Why?

People who are depressed are literally sick at heart: They have a significantly increased risk for cardiovascular disease, and no one knows exactly why. Three new studies have tried to explain this, and they arrive at subtly different conclusions.

The first, led by Dr. Mary Whooley of the Veterans Affairs Medical Center in San Francisco, studied 1,017 patients with coronary artery disease for an average of more than four years. Although the study found an association of depression with heart disease, when researchers statistically corrected for other medical conditions, disease severity and physical inactivity, the association disappeared.

They concluded with a relatively straightforward explanation: Depression leads to physical inactivity, and lack of exercise increases the risk for heart disease. The study appears in the Nov. 24 issue of The Journal of the American Medical Association.

A second study, published Tuesday in the Journal of the American College of Cardiology, provides a different perspective. It included more than 6,500 healthy men and women with an average age of 51. Researchers tested them for depressive symptoms and followed them for an average of more than seven years.