Comparison of the Effectiveness of Cognitive-Behavioral Therapy and Mindfulness-Based Therapy on Emotion Regulation and Psychological Flexibility in Patients with Major Depressive Disorder

The present study aimed to compare the effectiveness of Cognitive-Behavioral Therapy (CBT) and Mindfulness-Based Cognitive Therapy (MBCT) on emotion regulation and psychological flexibility in patients diagnosed with Major Depressive Disorder (MDD). This research employed a quasi-experimental design with a pre-test and post-test, including a control group. The statistical population consisted of individuals diagnosed with MDD who referred to the psychotherapy center at Imam Reza Hospital in 2025. Following an initial screening using the Structured Clinical Interview for DSM-5 (SCID-5), 45 participants who met the inclusion criteria were selected and randomly assigned to three groups of 15. The instruments used in the study included the Emotion Regulation Questionnaire (ERQ) by Gross and John, the Acceptance and Action Questionnaire-II (AAQ-II) by Hayes et al., the Beck Depression Inventory-II (BDI-II), and the SCID-5. Data were analyzed using multivariate analysis of covariance (MANCOVA). The results indicated that both CBT and MBCT interventions led to statistically significant improvements in emotion regulation and increases in psychological flexibility compared to the control group (p < 0.01). Furthermore, the MBCT group showed greater effectiveness in reducing rumination and enhancing acceptance, whereas CBT was more effective in reducing negative beliefs and increasing cognitive reappraisal. Both CBT and MBCT proved effective in enhancing emotion regulation and psychological flexibility in individuals with depression; however, each intervention offered specific advantages. These findings suggest that selecting the most appropriate therapeutic approach can be optimized by considering the individual needs of patients.