Mental Disorders Mediate the Relationship between Adverse Childhood Experiences and Suicidal Behavior in a High-Risk Population: A Counterfactual Analysis From Jeju Island.

Objectives: Jeju Island, Korea, is characterized by a significantly higher prevalence of adverse childhood experiences (ACE, 32.4%), elevated rates of mental disorders (34.6% vs. 22.9%), and lifetime suicidal thoughts (20.6% vs. 10.7%) compared to national averages. We investigated the mediating role of mental disorders in the pathway from ACE to suicidal behavior in Jeju.

Methods: Data from the Jeju Special Self-Governing Province Mental Health Survey 2023 (n = 703) were analyzed. Exposure was defined as experiencing at least one ACE from the 10-item Adverse Childhood Experience International Questionnaire (ACE-IQ-10). Depressive disorder, anxiety disorder, and alcohol use disorder were diagnosed using the Korean-Composite International Diagnostic Interview (K-CIDI). Suicidal behavior was defined as experiencing suicidal ideation, planning, or attempts. A counterfactual mediation model was used to evaluate the natural direct effect and natural indirect effect (NIE) of mental disorders.

Results: The total effect of ACE on suicidal behavior showed a risk difference of 0.353. When considering all three mental disorders simultaneously, the NIE was 0.276, accounting for 78.1% of the total effect. Stratification analyses revealed stronger total effects in women and older adults, while the proportion mediated was higher in women and younger adults.

Conclusions: In this ACE-prevalent population, mental disorders collectively mediated approximately three-quarters of the pathway from ACE to suicidal behavior. These findings, derived through robust counterfactual analysis, suggest that strengthening screening and management protocols for mental disorders among adults with a history of ACE may effectively prevent suicide in populations with high ACE prevalence.