Efficacy of Mindfulness-Based Cognitive Therapy for Self-Esteem, Psychological Well-being, and Happiness in Substance Use Disorder: A Randomized Controlled Trial

Abstract Substance use disorder (SUD), a major public health concern across the world, and also in India, is commonly associated with low self-esteem, reduced psychological well-being, and diminished happiness. Yet, rigorous trials of psychosocial interventions targeting these outcomes in rehabilitation settings remain scarce. This single-masked randomized controlled trial (RCT) examined the efficacy of an 8-week Mindfulness-Based Cognitive Therapy (MBCT) program, delivered alongside treatment as usual (TAU), in improving self-esteem, psychological well-being, and happiness among adults with SUD. Seventy-one men receiving inpatient rehabilitation at two centers in Bangalore, India, were block-randomized to an MBCT-plus-TAU group (n=36) or a TAU-only group (n=35); 30 participants per group completed all four assessments (baseline, post-intervention, and one- and three-month follow-up). Across the full sample, scores on all three outcomes improved significantly over time (all p<.001). A significant time x group interaction emerged for happiness (F(3,198)=5.51, p=.001, partial eta-squared=.087), with the MBCT group showing greater gains than the TAU group; interactions for psychological well-being and self-esteem were not significant. Mean gain scores indicated significantly greater improvements with MBCT than with TAU for happiness and self-esteem, but not for psychological well-being. These findings support MBCT as a valuable adjunctive intervention for SUD rehabilitation, with the most robust benefit observed for happiness. Trial registration: Clinical Trials Registry of India, CTRI/2025/09/094309 (Registered on 08/09/2025). Details are available at http://ctri.nic.in.