Mindfulness-based cognitive therapy, acceptance and commitment therapy, and positive psychotherapy for major depression

Objective: In the past two decades, newer psychotherapy treatments have emerged for the treatment of major depression. This review aimed to comprehensively synthesize the evidence for mindfulness-based cognitive therapy (MBCT), acceptance and commitment therapy (ACT), and positive psychotherapy (PPT) in treating a current episode of major depression. Methods: A systematic search of the Ovid MEDLINE, Embase, PsycINFO, and Cochrane databases was conducted for randomized controlled trials of MBCT, ACT, and PPT for major depression. Standardized mean differences were calculated with Hedges’ g to complete random-effects meta-analysis. Heterogeneity was assessed with the Cochran Q statistic and I² statistic. Subgroup analysis was conducted to further investigate heterogeneity. Results: A random-effects meta-analysis of 15 studies (MBCT, N=7; ACT, N=4; PPT, N=4) revealed that all three therapies showed efficacy in reducing symptoms of depression with a small favorable effect, compared with all control conditions (N=946; Hedges’ g=0.34; 95% confidence interval=0.14, 0.54; p,0.001). Cochrane’s Q statistic (Q=32, df=15, p=0.007) suggested significant heterogeneity (I²=53%). A mixed-effects model test for subgroup differences showed significant differences between active controls and treatment-as-usual controls (x²=15.3, df=1, p,0.001). Overall quality of evidence and publication bias were low. Conclusions: Meta-analysis shows that MBCT and ACT may be superior to inactive or treatment-as-usual controls and that PPT may be comparable to active controls for reducing symptoms of major depression after an acute course of therapy. However, the quality of the evidence was low. High-quality studies are needed to confirm the efficacy of these interventions.