Effectiveness of transdiagnostic preventive interventions for anxiety and depression in at-risk adolescents: A systematic review and meta-analysis

• Transdiagnostic preventive interventions significantly reduce anxiety and depression in at-risk adolescents. • This meta -analysis provides one of the first quantitative syntheses of selective and indicated transdiagnostic prevention in youth. • Large effect sizes were found for both anxiety and depressive symptoms. • Results were robust across sensitivity analyses and showed no evidence of publication bias. • Transdiagnostic prevention offers a flexible, efficient, and scalable approach for adolescent mental health. Preventing emotional problems during adolescence is a priority due to their increasing prevalence and associated impairment. In this context, transdiagnostic approaches have gained growing attention in the field of emotional disorders. However, evidence regarding the effectiveness of transdiagnostic interventions for adolescents in selective and indicated prevention remains limited. The aim of this systematic review and meta -analysis was to examine the effectiveness of transdiagnostic selective and indicated preventive interventions among adolescents. A systematic search was conducted in PubMed, CENTRAL, Scopus, Web of Science, and PsycINFO. A total of 3,451 records were identified. Studies including both randomised and non-randomised intervention designs were synthesised using a random-effects meta -analytic model with the Generic Inverse Variance method, based on pre–post intervention changes. After screening and applying the eligibility criteria, six studies were included in the systematic review and meta -analysis. The findings suggest that transdiagnostic preventive interventions may lead to significant reductions in symptoms of anxiety and depression and broader emotional difficulties among adolescents. However, these findings should be interpreted with caution due to the limited number of available studies. Additionally, most studies were conducted in a limited number of geographical contexts, which may impact the external validity of the results to other cultural settings. This study contributes to the literature by providing the first quantitative synthesis of transdiagnostic selective and indicated preventive interventions for adolescents, offering preliminary evidence on their potential benefits for youth at risk of developing emotional disorders.