Stressful life events and incident depression among U.S. military personnel

Purpose: Although stressful life events (i.e., stressors) and depression are often assumed to be linked, the relation between stressors and incident depression is rarely studied, particularly in the military. The National Guard is a part-time subset of the U.S. military for whom civilian life stressors may be particularly salient, due to the soldiers’ dual roles and frequent transitions between military and civilian life. Methods: We used a dynamic cohort study of National Guard members from 2010 to 2016 to investigate the relationship between recent stressful experiences (e.g., divorce) and incident depression, with an exploratory analysis of effect modification by income. Results: Respondents endorsing at least one of nine past-year stressful events (a time-varying exposure, lagged by 1 year) had almost twice the adjusted rate of incident depression compared to those with no stressful events (HR = 1.8; 95% CI 1.4, 2.4). This association may be modified by income: among individuals making under $80,000 per year, those with past-year stressors had twice the rate of depression compared to those with no stressors, but among those making over $80,000, past-year stressors were associated with only 1.2 times the rate of depression. Conclusion: Stressful life events outside of deployment are important determinants of incident depression among National Guard servicemembers, but the effect of these events may be buffered by higher income.