The largest meta-analysis to date of randomized controlled trials of mindfulness-based cognitive therapy (MBCT) for relapse prevention in recurrent depression was published in JAMA Psychiatry recently. Here two of the co-authors on the paper, Catherine Crane and Zindel Segal reflect on its findings and ask “What do we know? What does it mean? Where to next?”
A relatively large number of studies have now examined the effects of mindfulness-based cognitive therapy for people at different stages in the course of a depressive illness. However the new meta-analysis focuses on trials addressing the original intention of MBCT, to prevent relapse in recurrent depression and includes data from nine trials recruiting adults with a history of recurrent depression, comparing the effectiveness of MBCT with a range of comparators in preventing depression relapses over a sixty week period. Unlike previous meta-analyses, which have summarized effects at the study level, this study uses individual participant data. This enables us not only to ask the question, “What is the overall effectiveness of MBCT on depression relapses?,” but also to consider “What works for whom, how do participant characteristics (such as age and gender) influence these outcomes?” The meta-analysis focuses on nine trials of MBCT identified up to November 2014, with data available from 1258 participants. One Australian trial was identified during the search process as eligible for inclusion, but the authors could not release individual study data for ethical/legal reasons.
What do we know?
Is MBCT for recurrent depression effective? What about compared with other (active) treatments?
Consistent with the findings of previous meta-analyses, our work indicates that MBCT provides clear benefit over control conditions (comprising usual care in some studies and active controls in others), through reducing rates of relapse to depression over 60 weeks follow-up. Extending these findings, MBCT also appears to provide comparable benefits to active treatment controls, in general, and antidepressant controls in particular, although the reduction in risk of relapse to depression was larger for the comparison between MBCT and all control conditions than for MBCT and active treatment controls.
For whom is it most effective?
Across the studies there was no evidence to suggest that the relative benefit of MBCT compared to control conditions was significantly influenced by participant age, gender, sociodemographic status, educational level, participant age of onset of depression or number of prior depressive episodes. Unfortunately, information on ethnicity was collected inconsistently, but across studies the majority of participants were Caucasian and so it is not clear whether the benefits of MBCT would be similar in samples with greater ethnic and racial diversity. Participants who were experiencing more depression at entry to treatment showed a greater benefit of MBCT compared with other treatments than those who were less depressed, although those who were less depressed were not disadvantaged by receiving MBCT.
What about safety? Is MBCT safe?
Along with efficacy, it is important to consider the safety indications for MBCT. This is a subject Ruth Baer and Willem Kuyken discuss in a separate blog post. It is also being researched thoughtfully by researchers such as Willoughby Britton and raised by several commentators in the media. The meta-analysis gathered data on serious adverse events either from the original trial papers or if this data were not reported, directly from the authors. All the trials had well-trained MBCT teachers and included careful baseline assessment of patients. As with psychotherapy trials more generally information about safety and adverse events has only been collected more recently and the ways in which this information is collected varies somewhat from trial to trial. Nonetheless, where it was collected these data suggest that rates of serious adverse events were comparable across both MBCT and comparator groups and in no instance was a serious adverse event attributable to MBCT. This suggests that when MBCT is delivered according to the manual by well-trained MBCT therapists it is safe.
In Summary
The results of this meta-analysis are promising and suggest that MBCT can provide a viable relapse prevention intervention for people with a history of recurrent depression. The findings that there was no evidence to suggest a range of factors such as age and gender significantly influenced the effectiveness of MBCT, and that there was no evidence for an association between MBCT and the occurrence of serious adverse events increases our confidence that MBCT is acceptable for a broad range of people with recurrent depression.
The results of this meta-analysis are promising and suggest that MBCT can provide a viable relapse prevention intervention for people with a history of recurrent depression.
So What Does It All Mean? What Are the Remaining Questions
Although the largest meta-analysis of MBCT for depressive relapse prevention to date, the dataset still only reflects a relatively small number of trials. It is important to consider how this research fits into the broader research literature, what we don’t yet know and which questions future research might fruitfully address. Given the prevalence of depression and the fact that the current standard of care for relapse prevention is maintenance medication, there has been a lot of interest in the relative efficacy of MBCT’s preventive effects. This meta-analysis provides evidence that MBCT (combined with antidepressants or delivered alongside antidepressant tapering/discontinuation) is comparable to maintenance antidepressants alone in preventing subsequent relapse. It is, however, important to take int