Having heart disease and depression can increase the risk of heart attacks and death. Research suggests that up to 40 percent of heart disease patients experience depressive symptoms.
Recent studies point to unhealthy behaviors, like smoking, that are found in both depressed patients and those with heart disease. For patients with heart disease that are depressed, unhealthy behaviors may put them at an even higher risk of death.
A recent study suggested targeting smoking and lack of physical activity in depressed patients with heart disease may improve their chance of survival.
Siqin Ye, MD, of Center for Behavioral Cardiovascular Health, Columbia University Medical Center, and colleagues, led the study to determine if certain behaviors explained the increased risk of death in depressed patients with heart disease. The behaviors they looked at were alcohol use, smoking, physical activity and not taking medication.
The study included 4,676 patients with a history of heart disease. These patients were given a depression test. A total of 638 patients had significant depressive symptoms based on the test.
Researchers used a computer-assisted telephone interview, a physical examination of patients at their home and had the patients fill out questionnaires. The interview asked them questions about their behavior, for example if they smoked. The physical examination was done by a medical professional and included taking bodily fluid samples.
Overall, 19.6 percent of depressed patients with heart disease had a heart attack or died. This is compared to 16.3 percent that had heart disease but were not depressed.
The researchers also looked at four behaviors that could have an impact on the depressed patients' risks. Depressed patients that smoked and had low levels of physical activity had a significant increase in their risk of heart attack and death. Smoking increased their risk by 36.9 percent. Lack of physical activity had a 21.0 percent increased risk.
"A substantial proportion of the relationship between elevated depressive symptoms and the risk for myocardial infarction or death was explained by behavioral mechanisms, the most important of which were smoking and physical inactivity," authors commented in the study.
The authors noted some limitations in their study. The behaviors they looked at were self-reported and may have been underestimated. The study did not include all types of biological factors that could account for depression and cardiac risk. Also, the patients that were the most severely depressed may not have survived long enough to be included in the study. This study did not conclude any causality, only observations.
The study titled, "Behavioral Mechanisms, Elevated Depressive Symptoms, and the Risk of Myocardial Infarction or Death in Individuals with Coronary Heart Disease," was published online in the Journal of the American College of Cardiology. It was funded by the National Institute of Neurological Disorders and Stroke, National Institutes of Health and the Department of Health and Human Services. Dr. Monika Safford is a consultant with DiaDexus and receives salary support from Amgen and Pfizer for research studies. These companies are in the pharmaceutical or biotechnology industry.