A Randomized Controlled Trial of Group-Based Acceptance and Commitment Therapy for Major Depressive Disorder

Objective: Major depressive disorder (MDD) is a prevalent and debilitating psychiatric condition. This study developed a group-based acceptance and commitment therapy (GACT) program for MDD and conducted a randomized controlled trial to evaluate its effectiveness. The study aims to assess the effects of GACT and identify factors influencing depression recovery in patients with MDD in Korea. Methods: Individuals diagnosed with MDD, aged 18–40 years, were recruited. Fifty-nine participants were randomly assigned to either the GACT or waitlist control (WLC) group, with 50 participants (27 in GACT and 23 in WLC) successfully completing the program. Results: The GACT group demonstrated significant improvements in depression symptoms (Center for Epidemiological Studies-Depression Scale, CES-D), rumination (Ruminative Response Scale-Revised, RRS-R), experiential avoidance (Acceptance and Action Questionnaire-II, AAQ-II), and cognitive fusion (Cognitive Fusion Questionnaire, CFQ) compared to the WLC group (all ps<0.05). Correlation and multivariate regression analyses indicated that improvements in CES-D scores were associated with changes in AAQ-II scores. Conclusion: Our findings suggest that the 8-week GACT program has positive effects on depressive symptoms and ACT-related psychological processes in patients with MDD. This study highlights GACT as a promising group-based intervention for depression, potentially reducing the burden of individual psychological treatments.