Dismantling mindfulness-based cognitive therapy for recurrent depression implicates lack of differential efficacy for mindfulness training

What is already known on this topic?

Risk of relapse among patients diagnosed with major depressive disorder is high (>50% of those recovering from a first episode of depression, and approximately 80% of those with a history of two or more episodes),¹ and this risk increases with each successive depressive episode.² Several clinical trials have demonstrated that mindfulness-based cognitive therapy (MBCT) significantly reduces relapse risk among patients with three or more prior depressive episodes.³ Yet, MBCT contains multiple therapeutic elements, and the specific efficacy of the mindfulness training element in MBCT is unknown.

What does this paper add?

• This is the largest investigation of MBCT to date, and the first to use an active psychological treatment group as a control. By employing a dismantling design that compared MBCT to cognitive psychological education (CPE) and treatment-as-usual (TAU) control groups, this study sought to disentangle the specific effect of mindfulness training from psychoeducation and non-specific therapeutic factors.

• The use of a dismantling design with a well-matched CPE control group comprised all of the elements of MBCT except for mindfulness training represents a critical advance over previous studies.⁴

• MBCT, CPE and TAU demonstrated comparable efficacy, in contrast to prior studies, which demonstrated a clear advantage of MBCT over TAU. In a prespecified analysis, MBCT was shown to be significantly more efficacious than the other two conditions for individuals with high levels of childhood trauma.

Limitations

• Owing to the implementation of evidence-based guidelines in the UK, the strength of the TAU control condition may have contributed to the null results on depression relapse.

• The use of a dichotomous outcome measure, though clinically valid, may have limited sensitivity to detect between-group differences.

What next in research?

• Studies of other multimodal mindfulness-based interventions (eg, Mindfulness-Oriented Recovery Enhancement⁵) should employ dismantling designs to parse out the therapeutic effects of mindfulness meditation from other intervention components, such as compassion meditation, yoga, psychoeducation and group support.

• Double-blinding in psychological treatment studies can be extremely difficult. At minimum, future studies should conceal the identity of experimental and control treatments and use perceived treatment credibility/therapeutic expectancy as a covariate in outcome analyses.

Could these results change your practices and why?

Yes. On the whole, mindfulness training appears to be no more efficacious than psychoeducation or other common empirically supported interventions for preventing depressive relapse. That said, clinical trials examine the overall average effect of a treatment, and significant individual differences exist with regard to treatment response, depending on clinical presentation and underlying biobehavioural vulnerabilities. Clinicians and researchers should attend to predisposing characteristics (such as childhood trauma, as identified in the present trial) that might moderate treatment effects.