CHICAGO The main reason depressed heart disease patients are at higher risk for further heart trouble is because they exercise less and adopt other unhealthy habits, researchers said on Tuesday.
In their study of 1,017 heart disease patients whose conditions were stable, the 20 percent who were depressed were at significantly higher risk of cardiovascular problems.
Depression is about three times more common among heart attack patients than in the general population, and depression increases the risk of a second heart attack, earlier research showed.
Patients in the study who were depressed had a roughly one-third increased risk of heart attack, stroke or other cardiac event. But the higher risk disappeared after adjusting for patients' lack of physical activity, increased smoking rates and their tendency to stop taking medications properly.
"It's really difficult to tease out where the independent effect of depression is happening and where the other effects of cardiac disease are ending," said researcher Mary Whooley of the Veterans Affairs Medical Center in San Francisco.
"But the message is that once you account for those health behaviors the patients would not longer have this excess risk of cardiac events. The risk would go from one in 10 down to one in 15," she said in a telephone interview.
She said some patients get caught in a downward spiral, in which their depression leads them to exercise less, which deepens their depression.
Patients were divided into six categories depending on level of physical activity. They answered questions about whether they had done 15 to 20 minutes of brisk walking in the past month, swum, done general conditioning or participated in recreational sports.
The report, which appeared in the Journal of the American Medical Association, concluded that heart disease patients could be counseled to exercise more and adopt a healthier lifestyle by stopping smoking and adhering to a heart-healthy diet.
Two months ago, the American Heart Association issued a recommendation to routinely screen heart disease patients for depression to address the problem.
But a subsequent report based on a review of previous studies said there was little proof depressed patients live longer or fare better over the long term if they are screened for depression and treated with drugs and talk therapy.
(Editing by Michael Conlon and Doina Chiacu)