Transdiagnostic Internet-delivered intervention for children and adolescents with anxiety and depressive disorders: a randomized controlled trial.

Internalizing problems are the most common mental health problems encountered in youths. This study investigated the efficacy of a transdiagnostic Internet-delivered intervention (REBTonAd), delivered over 6 weeks. Our study included Romanian youths (aged 11-17) with a primary diagnosis of an anxiety and/or depressive disorder. Eligible participants (N = 106; Mage = 12.83, SD = 1.63) were randomly assigned to the REBTonAd group (n = 53) or the waitlist condition (WL) (n = 53), with outcomes assessed at baseline, post-test, and 6-month follow-up. At the post-test, the remission rate and clinical reliable change indices were higher in the REBTonAd group. Internalizing problems were reduced more in the REBTonAd group, with a moderate effect size (standardized mean difference = -0.60, 95% CI -0.96 to -0.25). Future research needs to test the effectiveness of this intervention compared to disorder-specific treatments and investigate its cost-effectiveness. This trial was prospectively registered at ClinicalTrials.gov (NCT04179526).