On June 22, a candidate in the governor's race in the U.S. state of Maryland withdrew, saying he is suffering from clinical depression and needs professional help. Depression is one of the most common psychiatric illnesses, and studies show it may be harmful to the heart. 

Mary Whooley

Dr. Mary Whooley is an internist in San Francisco, California. She decided to review all the published research she could find on the link between heart disease and depression. She said, "The majority of studies have found that depression is associated with an increased risk of heart attacks. This means that depression is not only affecting one's mental health, it may also affect one's physical health."

Dr. Whooley's study was published in the Journal of the American Medical Association. Among her findings  - that one out of every three heart failure patients suffers from depression. "It may be that patients with depression have elevated levels of stress hormones that might damage their heart or there may be behavioral consequences of depression such as not taking medications as prescribed, or not eating as well or not exercising that may damage the heart," Whooley said.

Wiley Cowan

A Swedish study released in December 2005 found that people diagnosed with depression earlier in life, between 25 and 50 years of age, have increased risk of developing coronary heart disease later on. The link between heart disease and depression makes sense to Wiley Cowan, who has had a quadruple bypass and suffered two strokes. "The heart issues surfaced just a few years ago, but I feel that I have suffered from depression for a great many years," he said.

Doctor with patient

The U.S. National Institute of Mental Health says nearly 15 million American adults are currently affected by a major depressive disorder. Dr. Whooley says the most surprising thing is that depression is extremely common and that more than half of the cases are never diagnosed or treated properly. Many studies link depression with serious physical illness. The National Institute of Mental Health reports that treating depression, especially in patients with serious illnesses, can improve the quality of their lives and even hasten recovery.