Short- and long-term incidence of obsessive–compulsive disorder after objectively recorded potentially traumatic events

Abstract The causal link between potentially traumatic events and obsessive–compulsive disorder (OCD) remains unclear due to reliance on retrospective self-reports and limited control for familial factors. Here, in this Swedish population-based cohort study, we identified 3,340,945 individuals born between 1975 and 2008 and prospectively examined the associations of objectively recorded assault/victimization and transport accidents with subsequent OCD diagnoses. Individuals exposed to assault/victimization, but not transport accidents, had an increased OCD risk (hazard ratio (HR) 1.73, 95% confidence interval (CI) 1.63–1.83), especially within the first year (HR 2.31, 95% CI 1.98–2.70), decreasing thereafter (HR 1.67, 95% CI 1.57–1.77). The association persisted in discordant full sibling comparisons (HR 1.37, 95% CI 1.23–1.54). Quantitative genetic modeling indicated that the phenotypic correlation ( r = 0.12) was primarily due to additive genetic (69%) and unique environmental factors (31%). These findings highlight a complex relationship between assault/victimization and OCD, involving both genetic vulnerability and individual environmental exposure.