Acceptance and commitment therapy versus traditional cognitive behavioral therapy: A systematic review and meta-analysis of current empirical evidence

Controversy remains about the empirical status of acceptance and commitment therapy (ACT) and its presumably different characteristics relative to traditional cognitive behavioral therapy (CBT). The current study aims to shed some light in this respect by conducting a systematic review and meta-analysis of the studies that have empirically compared ACT versus CBT. Sixteen studies comparing differential outcomes (N= 954) of ACT versus CBT in diverse problems were identified following several search strategies. The meta-analysis, which applied random and mixed effects models, showed that mean effect sizes on primary outcomes significantly favored ACT (Hedges’s g= 0.40). Mean effect sizes were not significant with anxiety symptoms whereas a positive trend for ACT was obtained in depression (g= 0.27) and quality of life (g= 0.25) at post-treatment. Likewise, ACT showed a greater impact on its putative processes of change (g= 0.38) and no differences were found regarding CBT proposed processes (g= 0.05). Nine of the sixteen studies conducted formal mediation analyses. Overall, ACT seemed to work through its proposed processes of change but CBT did not. Results are discussed highlighting the limitations of the current empirical evidence but also emphasizing the relevance of the current findings.