Alcohol use disorder and childhood adversity in the association between polygenic risk and suicidality.

OBJECTIVE: Suicidal ideation (SI) and suicide attempt (SA) are both influenced by genetic, behavioral, and environmental factors. Alcohol use disorder (AUD) and adverse childhood experiences (ACEs) may mediate or moderate the effects of genetic liability for suicidality. METHODS: Using data from 10,275 participants (43.8% female; 47.2% African-like genetic ancestry [AFR], 52.8% European-like genetic ancestry [EUR]), we tested whether polygenic scores (PGS) for SI and SA predicted lifetime suicidality outcomes. We evaluated whether AUD partially accounted for these associations and ACEs moderated the direct and indirect associations. RESULTS: The SA PGS was significantly associated with SA (AFR: b = 0.36, SE = 0.01; EUR: b = 0.17, SE = 0.01; both ps < 2e-16), but the SI PGS was not associated with SI (p > 0.55). AUD statistically mediated the association between the SA PGS and SA, accounting for approximately 2% of the total association in AFR individuals and 10% in EUR individuals (both ps < 2e-16). Notably, the proportion of the association that was accounted for by AUD decreased as ACEs exposure increased, from 4.30% to 0.54% in AFR individuals and from 13.31% to 3.44% in EUR individuals. In contrast, there was only very modest mediation and no moderated mediation for SI. CONCLUSIONS: Particularly among individuals with lower ACEs exposure, AUD accounted for a meaningful proportion of the association between genetic liability to SA and lifetime SA. These findings highlight different correlates across suicidality phenotypes and suggest potential clinical relevance for AUD in the association between genetic liability and SA.