Psychological mechanisms of change in reducing co-occurring social anxiety and alcohol use: A causal mediation analysis of the online Inroads intervention

Background: Research has documented the prevalence and treatment of co-occurring anxiety and alcohol use, but the mechanisms underlying treatment efficacy, especially in online interventions, remain unclear. This study investigated the potential behavioral, cognitive, and motivational mechanisms mediating the effectiveness of 'Inroads,' the first online early intervention for co-occurring anxiety and hazardous alcohol use in young adults. Methods: Data from an Australian randomized controlled trial with 123 participants aged 17-24 (M = 21.6) was used. Causal multiple mediation analysis tested whether improvements in social anxiety symptoms could jointly be attributable to reductions in maladaptive emotion regulation and alcohol use, and whether reductions in alcohol use (mean drinks per day) could jointly be attributable to reductions in maladaptive emotion regulation, alcohol motives (drinking to cope with anxiety and for enhancement), and alcohol outcome expectancies (tension reduction and social lubrication). Results: The results did not support a joint mediated effect for the hypothesized mechanisms in the social anxiety or alcohol use model. Conclusions: Additional research is required to further understand the specific mechanisms, driving reductions in social anxiety and alcohol use within integrated treatments. This is especially true for social anxiety where, there was no evidence to suggest that the hypothesized mediators contributed to change in social anxiety symptoms.