Self-Criticism as a Mechanism of Change in Compassion-Based Interventions: A Meta-Analytic Structural Equation Modelling Approach and Systematic Review.

Compassion-based interventions (CBIs) are effective transdiagnostic treatments for a wide range of psychopathological symptoms. While their efficacy is well established, their mechanisms remain insufficiently understood. Self-criticism (SC) has been proposed as a promising mechanism of change (MoC), given its central role in psychopathology and its theoretical link with CBIs. This study synthesises evidence from randomised controlled trials to examine whether reductions in SC mediate the effects of CBIs on psychopathological symptoms. Systematic searches in PubMed, Web of Science, Scopus and ProQuest identified 57 randomised controlled trials (n = 4877) of CBIs in adults reporting SC and psychopathological symptom outcomes, analysed using One-Stage Meta-Analytic Structural Equation Modelling (OMASEM). SC partially mediated the effects of CBIs on symptom reduction (e.g., depression, anxiety, eating disorders; indirect effect = -0.054, 95% CI [-0.085, -0.030]). Stronger mediation effects were observed in studies prescribing more daily home-practice minutes and shorter intervention duration. At posttreatment, CBIs achieved moderate reductions in SC (r = -0.20, 95% CI [-0.27, -0.13]) and psychopathological symptoms (r = -0.21, 95% CI [-0.27, -0.15]). Moreover, SC was positively correlated with psychopathological symptoms (r = 0.48, 95% CI [0.42, 0.54]), supporting partial mediation by SC. Considerable heterogeneity was observed across interventions and designs; 76.4% showed high risk of bias. These findings support SC as a potential MoC in CBIs and provide quantitative evidence for process-based formulations of CBIs. The results also highlight the clinical relevance of directly targeting SC in therapeutic practice and contribute to understanding the psychological processes underlying CBIs.