Does Mindfulness-Based Cognitive Therapy With Tapering Support Reduce Risk of Relapse/Recurrence in Major Depressive Disorder by Enhancing Positive Affect? A Secondary Analysis of the PREVENT Trial

Objective: Mindfulness-based cognitive therapy (MBCT) is a viable alternative to maintenance antidepressant medication (M-ADM) to reduce risk of relapse/recurrence (RR) in recurrent depression, but its mechanism of action is not yet fully articulated. This secondary analysis of the PREVENT trial examined if MBCT with support to taper medication (MBCT-TS) reduces risk of RR in part by enhancing positive affect (PA). Method: In a single-blind, parallel, group randomized controlled trial, adults with >= 3 prior depressive episodes, but not currently in episode and who were taking M-ADM, were randomized to receive either MBCT-TS or ongoing maintenance M-ADM. The primary outcome was RR over 24-month follow-up. Levels of positive affect were assessed at intake and posttreatment. The original PREVENT trial was preregistered (ISRCTN 26666654), but this secondary analysis was not. Results: Four hundred and twenty-four individuals (predominantly female and of White British ethnicity) were recruited, with 212 randomized to each arm. MBCT-TS led to significantly greater PA relative to M-ADM at posttreatment assessment (Delta = 2.78, 95% CI [1.47, 4.08], p < .001). RR was experienced during follow-up by 194 individuals (100 M-ADM; 94 MBCT-TS). Greater intake PA predicted a reduced hazard of RR across treatments (p < .001; hazard ratio = .96, 95% CI [0.94, 0.98]). In individuals who had not relapsed by posttreatment with complete data (121 M-ADM; 145 MBCT-TS), greater increase in PA from intake to posttreatment mediated reduced risk of subsequent RR (p = .04). Conclusions: These findings suggest that greater levels of PA predict reduced risk of RR and that MBCT-TS in part acts to protect from RR when withdrawing from M-ADM by increasing PA.