Efficacy of School-Based Third-Wave Cognitive Behavioral Therapies on Depression, Anxiety, and Resilience in Youth: A Three-Level Meta-Analysis

Project Description Background and Rationale The trajectory of youth mental health has escalated into a systemic public health crisis, characterized by a precipitous rise in internalizing disorders such as anxiety and depression. Because traditional clinical models are structurally ill-equipped to meet this demand, schools have emerged as the sole ecological platform capable of delivering universal prevention at scale. While traditional "second-wave" Cognitive Behavioral Therapy (CBT) relies on "top-down" cognitive restructuring that may exceed youth neurodevelopmental readiness, "third-wave" therapies (e.g., Mindfulness, Acceptance and Commitment Therapy, and Yoga) offer a developmentally congruent alternative. These interventions utilize "bottom-up" regulatory strategies to target physiological arousal directly, potentially bypassing the underdeveloped prefrontal cortex. Despite this strong theoretical rationale, existing empirical evidence remains inconsistent, particularly regarding the "depression paradox," where interventions show null or inconsistent findings for depression while improving anxiety. Furthermore, prior meta-analyses have pervasively relied on traditional two-level models that ignore the nested structure of school-based data (dependent effect sizes), creating "false precision" and inflating Type I error rates. Purpose of the Study The primary purpose of this research is to resolve existing empirical discrepancies by conducting a comprehensive three-level meta-analysis of school-based third-wave CBT interventions. By synthesizing data from randomized controlled trials (RCTs) and cluster randomized controlled trials (cRCTs), this study aims to rigorously evaluate the efficacy of these interventions across three distinct psychological outcomes: depression, anxiety, and psychological resilience in youth aged 6 to 18. Crucially, by employing a three-level framework to account for intra-study dependency, this project seeks to correct the methodological biases of prior reviews and establish a highly precise baseline of treatment effects. Expected Outcomes and Key Investigations This project goes beyond the binary question of whether these programs work, aiming to answer how efficiently they work across different symptom domains. The expected outcomes and investigations include: Precise Efficacy Estimates: Providing conservative and accurate pooled effect sizes (Hedges' g) for anxiety, depression, and resilience by appropriately partitioning variance into sampling error, within-study variance, and between-study variance. Evaluation of the "Depression Paradox": Systematically determining whether the lack of efficacy for depressive symptoms is a consistent phenomenon across the broader literature or an artifact of specific trials. Dose-Response Analysis: Utilizing meta-regression to examine intervention duration (in weeks) as a continuous moderator. This will determine whether longer therapeutic programs yield proportionally greater benefits or if comparable effects can be achieved within shorter, more scalable timeframes. Implementation Guidance: Offering evidence-based recommendations for school administrators and policymakers regarding resource allocation, specifically whether to prioritize intervention duration or implementation fidelity.