The Efficacy of Mindfulness-Based Cognitive Therapy as a Public Mental Health Intervention for Adults with Mild to Moderate Depressive Symptomatology: A Randomized Controlled Trial

Objective Although there has been growing evidence for the efficacy of mindfulness-based cognitive therapy (MBCT) for different clinical populations, its effectiveness as a public mental health intervention has not been studied. The present study evaluates a community-based MBCT intervention for adults with mild to moderate depressive symptomatology in a large multi-site, pragmatic randomized controlled trial. Method The participants with mild to moderate depressive symptomatology were recruited from the general population and randomized to the MBCT intervention (n = 76) or to a waiting list control group (n = 75). Participants completed measures before and after the intervention. Participants in the experimental condition also completed these measures at a 3-month follow-up. Results In the experimental condition significant reductions in depression, anxiety, and experiential avoidance, and improvements in mindfulness and emotional- and psychological mental health were found, compared to the waiting list (effect sizes Cohen's d = 0.31–0.56). These effects were sustained at the 3-month follow-up. The likelihood of a clinically significant change in depressive symptoms was significantly higher for the MBCT group [odds ratio (OR) 3.026, p<0.01 at post-treatment; NNT = 5.10]. Discussion MBCT as a public mental health intervention for adults with mild to moderate depressive symptoms seems effective and applicable in a natural setting

Means and standard deviations for process measures, results of ANOVA and Cohen's d for intervention effects.

<p><i>Note</i>. AAQ-II, Acceptance and Action Questionnaire-II; ANOVA, Analysis of variance; FFMQ, Five Facet Mindfulness Questionnaire; Observe, observing; Describe, describing; ActAware, acting with awareness; NonJudge, non-judging of inner experience; NonReact, non-reactivity to inner experience.</p>a<p> Follow-up for intervention group and post-treatment for waiting list group.</p><p>Means and standard deviations for process measures, results of ANOVA and Cohen's d for intervention effects.</p

Baseline characteristics of the total sample, MBCT intervention and waiting list control condition.

<p><i>Note</i>. MDE, major depressive episode.</p>a<p> No significant differences between intervention and control condition (t-test with <i>P</i><0.05).</p>b<p> No significant differences between intervention and control condition (chi-square-test with <i>P</i><0.05).</p><p>Baseline characteristics of the total sample, MBCT intervention and waiting list control condition.</p

Participant flow.

<p>MDE  =  major depressive episode.</p

Means and standard deviations for outcome measures and results of ANCOVA for intervention effects, and Cohen's d.

<p><i>Note</i>. ANCOVA, Analysis of covariance; CES-D, Center for Epidemiologic Studies - Depression.</p><p>Scale; HADS-A, Hospital Anxiety and Depression Scale - Anxiety subscale; MHC-SF, Mental Health Continuum - Short form; EM, emotional; SOC, social; PSY, psychological.</p>a<p> Unadjusted condition means and standard deviations (SD).</p>b<p> F-value, corrected for baseline values.</p>c<p> Follow-up for intervention group and post-treatment for waiting list group.</p><p>Means and standard deviations for outcome measures and results of ANCOVA for intervention effects, and Cohen's d.</p