Transdiagnostic psychological processes underlying anxiety, depression, alcohol use disorder, and problematic social media use: A Bayesian RDoC-informed study.

Identifying transdiagnostic psychological processes underlying both internalizing and behavioral conditions is a central goal in contemporary clinical psychology, yet no prior study to our knowledge has simultaneously examined multiple theoretically grounded transdiagnostic domains across these outcomes within a unified Bayesian RDoC-informed framework. The present study investigated the contribution of well-established transdiagnostic psychological processes (i.e., emotion regulation, dispositional self-regulation, psychological flexibility, mentalization, insecure attachment, and childhood maltreatment) to symptoms of anxiety, depression, alcohol use disorder (AUD), and problematic social media use (PSMU). A large community sample of adults (N = 1997) completed self-report measures. Bayesian model averaging was employed to identify the most relevant predictors of each outcome while accounting for model uncertainty. Across multivariate Bayesian models including all predictors, initiatory self-control was consistently identified as a relevant predictor and showed 95% Bayesian credibility intervals not including zero across all outcomes. Emotional abuse and anxious attachment were consistently identified as relevant predictors of anxiety, depression, and PSMU, whereas sexual abuse was selectively associated with depression and AUD. Among mentalization dimensions, certainty about mental states showed credible negative associations with anxiety and PSMU, whereas uncertainty showed credible positive associations with anxiety and depression. Psychological flexibility showed negative associations with anxiety and depression, but not with behavioral outcomes. These findings highlight initiatory self-control, i.e., the ability to initiate goal-directed behaviors, as a core transdiagnostic process, supporting process-based models of psychopathology. Our results support the use of integrated, standardized psychological assessments capturing core transdiagnostic and condition-specific dimensions to facilitate early identification of at-risk individuals.