It’s estimated that about 20% of patients with coronary heart disease (CHD) meet the criteria for major depression, and as many as 40% have at least some depressive symptoms. Depression among CHD has been consistently shown to increase the risk of adverse events, including death and myocardial infarction (MI). National guidelines recommend screening and treating depression in patients with CHD, but there is still a lack of complete understanding of the mechanisms by which depression increases cardiac risk. Gaining knowledge on this relationship may lead to new approaches for improving outcomes in this patient group.
More Clarity on CHD & Behavioral Mechanisms
Recent studies have indicated that behavioral mechanisms appear to explain part of the increased risk for adverse cardiac outcomes conveyed by depression. In a study published in the Journal of the American College of Cardiology, my colleagues and I sought to clarify these relationships further. Using data from more than 4,600 patients with CHD, we examined the explanatory role played by alcohol use, smoking, physical inactivity, and medication non-adherence in the association between depressive symptoms and MI or death.
According to our results, self-reported behavioral mechanisms explained a substantial proportion of the excess risk of MI or death that was associated with elevated depressive symptoms in CHD patients. Collectively, the four behavioral mechanisms explained 40% of the increased risk for MI or death conveyed by elevated depressive symptoms. Smoking and physical inactivity were the most substantial behavioral mechanisms contributing to this risk. These mechanisms each accounted for about 20% of the relationship between elevated depressive symptoms and cardiac risk.
We also confirmed that patients with CHD who had more depressive symptoms were at greater risk of MI or death. Taken together, our analysis suggests that behavioral mechanisms such as smoking and physical inactivity are key contributors to this increased risk.
Coronary Heart Disease Moving Forward
In addition to the observed mechanistic insights, our study has important implications for future research and potential interventions for patients with CHD who are depressed. For example, there might be a role for intermediary interventions that emphasize certain health behaviors, especially smoking cessation and physical activity. Despite the presence of guidelines, many patients are still struggling to meet current recommendations for smoking cessation and exercise. Going forward, there is an urgent need for more attention to the impact of depression, behavioral mechanisms, and CHD so that we can improve outcomes for these patients in the future.
Siqin Y, Muntner P, Shimbo D, et al. Behavioral mechanisms, elevated depressive symptoms, and the risk for myocardial infarction or death in individuals with coronary heart disease: the REGARDS (Reason for Geographic and Racial Differences in Stroke) study. J Am Coll Cardiol. 2013;61:622-630. Available at: http://content.onlinejacc.org/article.aspx?articleid=1555240.
Blumenthal JA, Sherwood A, Babyak MA, et al. Exercise and pharmacological treatment of depressive symptoms in patients with coronary heart disease: results from the UPBEAT (Understanding the Prognostic Benefits of Exercise and Antidepressant Therapy) study. J Am Coll Cardiol. 2012;60:1053-1063.
Pozuelo L, Tesar G, Zhang J, et al. Depression and heart disease: what do we know, and where are we headed? Cleve Clin J Med. 2009;76:59-70.
Whooley MA, de Jonge P, Vittinghoff E, et al. Depressive symptoms, health behaviors, and risk of cardiovascular events in patients with coronary heart disease. JAMA. 2008;300:2379-2388.
Davidson KW, Rieckmann N, Clemow L, et al. Enhanced depression care for patients with acute coronary syndrome and persistent depressive symptoms: coronary psychosocial evaluation studies randomized controlled trial. Arch Intern Med. 2010;170:600-608.
Berkman LF, Blumenthal J, Burg M, et al. Effects of treating depression and low perceived social support on clinical events after myocardial infarction: the Enhancing Recovery in Coronary Heart Disease Patients (ENRICHD) Randomized Trial. JAMA. 2003;289:3106-3116.