Physical inactivity, depression, and risk of cardiovascular mortality

Purpose: Studies indicate that depression may increase risk of cardiovascular disease (CVD) in addition to classical risk factors. One of the hypotheses to explain this relation is that depressed subjects become physically inactive. We set out to determine the role of physical inactivity in the relation between depressive symptoms and cardiovascular mortality. Methods: Data were used from the population-based prospective Finland, Italy, and the Netherlands Elderly (FINE) Study. Depressive symptoms were measured with the Zung Self-Rating Depression Scale in 909 elderly men, aged 70-90 yr, free of CVD and diabetes at baseline in 1990. Physical activity was assessed with a questionnaire for retired men. Hazard ratios (HR) for 10-yr cardiovascular mortality were calculated, adjusting for demographics and cardiovascular risk factors. Results: At baseline, men with more depressive symptoms were less physically active (722 min.wk(-1); 95% confidence interval (CI), 642-802) than men with few depressive symptoms (919 min.wk(-1); 95% CI, 823-1015). During 10 yr of follow-up, 256 (28%) men died from CVD. The adjusted HR of cardiovascular mortality for a decrease of 30 min.d(-1) in physical activity was 1.09 (95% CI, 1.04-1.14). An increase in depressive symptoms with one standard deviation was associated with a higher cardiovascular mortality risk (HR = 1.42; 95% CI, 1.26-1.60). After additional adjustment for physical activity the risk decreased (9%), but an independent risk remained (HR = 1.37; 95% CI, 1.21-1.56). The excess risk on cardiovascular mortality attributable to the combined effect of depressive symptoms with inactivity was 1.47 (95% CI, -0.17 to 3.11). Conclusions: In the present study, the increased risk of depressive symptoms on cardiovascular mortality could not be explained by physical inactivity. However, our results suggest that depressive symptoms and physical inactivity may interact to increase cardiovascular mortality risk.