Heart disease and depression share a circular relationship: In some cases, heart disease can bring about depression, with an estimated one in six heart-attack sufferers facing clinical depression after the event, which can increase their mortality rate to 17 percent. In other cases, depression has been linked to a higher likelihood of cardiovascular disease. One of the most recent studies, conducted jointly by the Washington University School of Medicine and the Veterans Administration, suggests that developing depression symptoms is a greater predictor for heart disease than family history.

The study, published at the annual meeting of the American Psychosomatic Meeting in Chicago in the beginning of March, was based on data compiled from more than 1,200 male twins who served in the Vietnam War. The men were interviewed in 1992 and again in 2005. Researchers found that the participants who reported that they suffered from depression in 1992 were twice as likely as their non-depressed peers to develop heart disease in the years leading up to the second interview.

Interestingly, a long-held assumption that depression is a contributing factor to hypertension has been recently challenged by researchers at VU University Medical Center in Amsterdam. Their findings, published in an online version of Hypertension at the end of February, suggest that depression is actually linked to low blood pressure, and tricyclic antidepressants, such as imipramine, are in fact responsible for raising blood pressure. According the National Institute of Mental Health, however, this class of antidepressants has been eclipsed in recent years by selective serotonin reuptake inhibitors (SSRIs) such as Prozac and serotonin-norepinephrine reuptake inhibitors (SNRIs) like Effexor. But another study published in the March 17 issue of the Journal of the American College of Cardiology found that sudden cardiac death might be associated with the use of antidepressants, though the researchers caution that they weren’t sure if the link was due to the medications or the depression they were treating.

Despite these recent findings, if you suspect that you may be among the estimated 18 million Americans who suffer from depression—which is defined by loss of interest in activities you once enjoyed or feelings of sadness that last more than two weeks—you should seek treatment, especially if you have been diagnosed or are prone to heart disease.

A report published in the October 21, 2008, issue of Circulation stated that SSRIs such as Zoloft (Registered) and Celexa have been determined to be safe for people with coronary heart disease and pointed to a study in which patients who were treated with an SSRI enjoyed a 42 percent reduction in death and recurrent heart attack.