Abstract
Background: Although depressive symptoms are shown to associate with mortality, few controlled studies have examined major depressive disorder (MDD) as a risk factor for premature death in young adults. We studied the relationship of MDD and history of suicide attempt (an alternative measure of depression) with non-suicide death and cardiovascular death in a US cohort of young adults. Additionally, we examined the role of smoking and BMI in mediating this relationship.
Methods: We studied 7611 adults aged 17-39 years without cardiovascular (CV) disease from the NHANES III (1988-1994) study. MDD and history of suicide attempt were assessed via the Diagnostic Interview Schedule. Detailed data on traditional cardiovascular risk factors and health behaviors, as well as mortality and cause of death data through 2006 were assessed. Longitudinal analysis was carried out using Cox proportional hazards models.
Results: The mean age was 28.1 +/- 6.6 years, with 241 (3.2%) non-suicide and 47 (0.6%) cardiovascular deaths occurring during a median of 14.9 years follow-up. At onset, 7.0% were diagnosed with MDD, 5.4% attempted suicide, and 10.7% had at least one of the two. In models adjusted for age, plasma cholesterol, race, systolic BP, and education, MDD (HR 3.0, p<0.001) and history of suicide attempt (HR 3.0, p<0.001) were associated with non-suicide death in males only (gender interaction: p<0.01 for MDD and p=0.08 for suicide). In adjusted analyses, those with MDD and/or history of suicide attempt had increased risk for cardiovascular mortality (HR 2.8, p=0.008) in both sexes. When adding BMI and smoking to the model for cardiovascular death, the HR decreased by 18% to 2.3 (p=0.03). Similar decreases in effect size were observed for the association of MDD (HR 2.7, p<0.001) and history of suicide attempt (HR 2.5, p=0.003) with non-suicide mortality among males.
Conclusion: Among young, mostly healthy individuals, major depression and history of suicide attempt are important risk factors for premature non-suicide death in men, as well as cardiovascular death in both sexes. Smoking and health behaviors that increase BMI (such as overeating and sedentary activity) may play a role, but do not completely account for the association.