We conducted a 26-month follow-up of a previously reported 12-month study that compared mindfulness-based cognitive therapy (MBCT) to a rigorous active control condition (ACC) for depressive relapse/recurrence prevention and improvements in depressive symptoms and life satisfaction. Participants in remission from major depression were randomized to an 8-week MBCT group (n = 46) or the ACC (n = 46). Outcomes were assessed at baseline; postintervention; and 6, 12, and 26 months. Intention-to-treat analyses indicated no differences between groups for any outcome over the 26-month follow-up. Time to relapse results (MBCT vs. ACC) indicated a hazard ratio = .82, 95% CI [.34, 1.99]. Relapse rates were 47.8% for MBCT and 50.0% for ACC. Piecewise analyses indicated that steeper declines in depressive symptoms in the MBCT vs. the ACC group from postintervention to 12 months were not maintained after 12 months. Both groups experienced a marginally significant rebound of depressive symptoms after 12 months but were still improved at 26 months compared to baseline (b = -4.12, p <= .008). Results for life satisfaction were similar. In sum, over a 26-month follow-up, MBCT was no more effective for preventing depression relapse/recurrence, reducing depressive symptoms, or improving life satisfaction than a rigorous ACC. Based on epidemiological data and evidence from prior depression prevention trials, we discuss the possibility that both MBCT and ACC confer equal therapeutic benefit. Future studies that include treatment as usual (TAU) control conditions are needed to confirm this possibility and to rule out the potential role of time-related effects. Overall findings underscore the importance of comparing MBCT to TAU as well as to ACCs.

Objective

We evaluated the comparative effectiveness of mindfulness-based cognitive therapy (MBCT) versus an active control condition (ACC) for depression relapse prevention, depressive symptom reduction, and improvement in life satisfaction.

Method

Ninety-two participants in remission from major depressive disorder with residual depressive symptoms were randomized to either an 8-week MBCT or a validated ACC that is structurally equivalent to MBCT and controls for nonspecific effects (e.g., interaction with a facilitator, perceived social support, treatment outcome expectations). Both interventions were delivered according to their published manuals.

Results

Intention-to-treat analyses indicated no differences between MBCT and ACC in depression relapse rates or time to relapse over a 60-week follow-up. Both groups experienced significant and equal reductions in depressive symptoms and improvements in life satisfaction. A significant quadratic interaction (Group × Time) indicated that the pattern of depressive symptom reduction differed between groups. The ACC experienced immediate symptom reduction postintervention and then a gradual increase over the 60-week follow-up. The MBCT group experienced a gradual linear symptom reduction. The pattern for life satisfaction was identical but only marginally significant.

Conclusions

MBCT did not differ from an ACC on rates of depression relapse, symptom reduction, or life satisfaction, suggesting that MBCT is no more effective for preventing depression relapse and reducing depressive symptoms than the active components of the ACC. Differences in trajectory of depressive symptom improvement suggest that the intervention-specific skills acquired may be associated with differential rates of therapeutic benefit. This study demonstrates the importance of comparing psychotherapeutic interventions to active control conditions.