Late-adolescent Risk Factors for Suicide and Self-Harm in Middle-Aged Men: Explorative Prospective Population-Based Study

Background Recent reports show alarmingly high rates of suicide in middle-aged men, yet there are few long-term prospective studies that focus on suicidal behaviour in men in this age group. Aims To prospectively explore associations of potential risk factors at age 18 with suicide and self-harm in middle-aged men. Method A population-based Swedish longitudinal cohort study of male conscripts with no history of self-harm at enlistment in 1968-1989 (n= 987 583). Conscription examinations included measures of cognitive performance, stress resilience, psychiatric diagnoses, body mass index (BMI), cardiovascular fitness and muscle strength. Suicides and self-harm at age 45-65 years were identified in the National Hospital Register and Swedish Cause of Death Register. Risks were calculated using Cox proportional hazards models. Results Low stress resilience (cause-specific hazard ratio CHR = 2.31, 95% CI 1.95-2.74), low cognitive ability (CHR = 2.01, 95% CI 1.71-2.37) as well as psychiatric disorders and low cardiovascular fitness in late adolescence were associated with increased risk for suicide in middle-aged men. Similar risk estimates were obtained for self-harm. In addition, high and low BMI as well as low muscle strength were associated with increased risk of self-harm. Associations also remained significant after exclusion of men with self-harm before age 45. Conclusions This prospective study provides life-course perspective support that psychological and physical characteristics in late adolescence may have long-lasting consequences for suicidal behaviour in middle-aged men, a very large population at heightened risk of suicide.