Mindfulness-based exposure and response prevention in individuals with comorbid obsessive-compulsive and major depressive disorders: a randomized controlled trial

This randomized controlled trial examined whether mindfulness-based exposure and response prevention (MB-EX/RP) improves outcomes for adults with comorbid obsessive-compulsive disorder (OCD) and major depressive disorder (M, addressing cognitive rigidity and emotion dysregulation that can limit standard exposure and response prevention. Fifty-four participants were assigned to MB-EX/RP or standard exposure and response prevention; 40 completed treatment (20 per group) across 17 sessions. OCD symptom severity, as measured by the Yale–Brown Obsessive Compulsive Scale (Y-BOCS), showed a significant Time × Group interaction, F(1, 38) = 3.37, p <.05, indicating greater reductions in MB-EX/RP relative to EX/RP, together with a between-group effect, F(1, 38) = 4.88, p <.05, and a large overall time effect (η²p =.83). MB-EX/RP was also associated with greater improvements in obsessive beliefs, F(1, 38) = 11.60, p <.001; dispositional mindfulness, F(1, 38) = 16.70, p <.001; and mental well-being, F(1, 38) = 5.38, p <.05. Depressive symptoms improved significantly in both groups, with a significant between-group difference favoring MB-EX/RP, F(1, 38) = 14.90, p <.001; however, the Time × Group interaction was not significant (p =.19), indicating similar trajectories of change. Treatment gains were maintained descriptively at four-month follow-up, and concurrent antidepressant use did not influence outcomes. These findings suggest that integrating mindfulness into exposure-based treatment may enhance clinical outcomes in complex comorbid presentations. Trial registration: CTRI/2021/10/037545 (Registered on 25/10/2021). Details are available at http//ctri.nic.in.