Depression, Heart Attack Link Tracked to Autonomic Nervous System

Depression can not only set the stage for a heart attack, but increase the risk of death after a person has already had a heart attack, mounting evidence suggests.

But how might depression negatively affect the heart after a heart attack?

Perhaps via the autonomic nervous system, a new study reveals.

The study was published in the October 23 issue of Circulation, a journal of the American Heart Association, and was conducted by Robert Carney, Ph.D., a professor of medical psychology at Washington University School of Medicine in St. Louis, and coworkers.

A total of 673 persons participated in the study by Carney and his team. All had suffered heart attacks a month before they were enrolled. At the time of enrollment all were also assessed for the presence of major or minor depression according to DSM-IV criteria. Of the 673 subjects, 307 were found to be depressed.

All the subjects then received electrocardiographic monitoring to determine their heart-rate variability. Heart-rate variability measures cardiac autonomic function, which includes the sympathetic and parasympathetic nervous system and helps control blood vessel size, blood pressure, the heart’s electrical activity, and its ability to contract. Low heart-rate variability reflects excessive sympathetic or reduced parasympathetic function and is a strong independent predictor of death after heart attack.

Sixteen percent of the depressed subjects, but only 7 percent of the nondepressed subjects, were found to have a low heart-rate variability. Thus altered cardiac autonomic nervous system activity may be the pathway through which depression kills people after a heart attack, the researchers concluded.

The study was partially underwritten by the National Institutes of Health.

An abstract of the report, “Depression, Heart Rate Variability, and Acute Myocardial Infarction,” can be accessed online at http://circ.ahajournals.org/content/vol104/issue17/index.shtml by clicking on “Cardiovascular News” and then the title of the report. ▪