Additional studies augment this theory. Research led by Dr. Nancy Frasure-Smith of the Montreal Institute of Health followed over 200 heart attack patients and found those who suffered from depression were four times as likely to die within six months of their heart attacks as those patients who were not depressed. The researchers found that depression was just as good a predictor of looming death as previous heart attacks and poor heart functioning. Dr. Robert M. Carney, a professor of medical psychology at Washington University in St. Louis, found patients who had just been diagnosed with heart disease and were also depressed were twice as likely as non-depressed new heart patients to suffer from a heart attack or require bypass surgery within 12 months of their diagnosis. Doctors are also concerned that many depressed heart patients are either not treated at all for their depression, misdiagnosed when they do seek treatment, or treated incorrectly, such as being prescribed sedatives, which makes depression worse.
More recent research seems to indicate that depression leads to heart disease.
In a study led by Dr. William W. Eaton of the Johns Hopkins School of Hygiene and Public Health in Baltimore, researchers followed approximately 1,500 healthy people with no evidence of heart disease over a 14 year period from 1981 to 1995. During the study, researchers found that subjects who were depressed suffered from heart attacks at a rate four times greater than subjects who did not suffer from depression. Further research in biochemical changes caused by depression may lead to the answers. Research shows people who suffer from depression have hearts that beat faster, even when sleeping. All of these factors result in more stress on the blood vessels and the heart.