The relationship between major depression and nonsuicide mortality for U.S. adults: the importance of health behaviors.

OBJECTIVES

We aim to elucidate the role of health behaviors and health conditions in the association between depression and mortality. First, we examine the relationship between major depression and nonsuicide mortality among U.S. adults aged 50 and older. Second, we examine the relationship between major depression and cardiovascular disease and cancer, by baseline disease status. Third, we examine the role of health behaviors as potential mediators of the association between major depression and cause-specific mortality.

METHODS

We use data from the 1999 National Health Interview Study linked to the 2006 National Death Index (N = 11,369; M age = 65, deaths = 2,162) and Cox proportional hazards models to describe the relationships among major depression, health behaviors (alcohol use, cigarette smoking, physical activity), and nonsuicide mortality. We examine cause-specific mortality (cardiovascular and cancer) by baseline disease status.

RESULTS

Major depression remains associated with a 43% increase in the risk of death over the follow-up period, after we account for sociodemographic characteristics, health behaviors, and health conditions. Major depression is associated with 2.68 times the risk of cardiovascular disease mortality among those who did not have cardiovascular disease at baseline and 1.82 times for those with baseline cardiovascular disease. Health behaviors reduce the hazard ratio by 17% for all nonsuicide mortality, 3% for cardiovascular disease mortality, and 12% for cancer mortality.

DISCUSSION

Our results provide evidence of the important role of health behaviors and health conditions in the depression-mortality relationship and highlight the importance of identifying risk factors for depression among aging adults.