Co-occurring Anxiety and Alcohol Use: Advancing Prevention and Early Intervention

Abstract

Anxiety and alcohol use frequently co‑occur, contributing to more complex symptoms, clinical presentations, and poorer outcomes. Yet the mechanisms driving this comorbidity remain unclear, and gaps persist in prevention and early intervention. This thesis aimed to advance understanding of anxiety–alcohol comorbidity by i) clarifying their relationship and ii) improving early interventions for co‑occurring problems. Study 1 presented the first systematic review and meta‑analysis synthesising mediators and moderators of the anxiety–alcohol link. Across 315 effects from 55 studies, findings identified potential targets for prevention and intervention, including age, externalising symptoms, perceptions of peer alcohol use, and positive family experiences. Study 2 examined associations between anxiety and hazardous alcohol use across seven timepoints from early adolescence to young adulthood. Consistent positive within developmental stage associations were observed up to age 16. Although externalising symptoms, drinking motives, and sex moderated cross‑sectional relationships, no consistent longitudinal moderation effects emerged in early adolescence. Study 3 used causal inference methods to test mechanisms of change in the first online intervention for youth with co‑occurring anxiety and alcohol use. Emotion regulation and alcohol use did not mediate social anxiety outcomes, and emotion regulation, positive alcohol expectancies, and motives did not mediate alcohol outcomes. Study 4 used mixed methods to identify barriers and enablers to engagement with online treatment among young adults with co‑occurring anxiety and alcohol concerns. Individual factors, rather than program‑related factors, were the primary barriers to engagement. Collectively, this thesis advances understanding of co‑occurring anxiety and alcohol use and provides evidence to inform prevention, early intervention, and treatment, particularly for youth.