A meta-analysis of Mindfulness Based Interventions (MBIs) show that MBIs are effective in reducing acute symptoms of depression but not anxiety.

Objective of the review: To determine the effectiveness of mindfulness based interventions (MBIs) in reducing primary symptomology in people experiencing current episodes of anxiety or depression through a meta-analysis of randomised controlled trials (RCTs). Search strategies: A meta-analysis of 1517 records were identified though MEDLINE, Web of Science, Scopus, Proquest and PsychINFO; as well as three leading clinical trial registers using the key phrases of Mindfulness-Based Cognitive Therapy (MBCT), Mindfulness Based Stress Reduction (MBSR)combined with anxiety and depression. Selection criteria: The selection criteria included: (i) RCTs; (ii) participants 18 years or older; (iii) mindfulness was a core part of the intervention used both within therapy and between therapy sessions; (iv) studies included a psychometrically reliable and valid outcome measure of depression and anxiety; and (v) all participants met the full criteria for a current episode of a DSM IV diagnosis of either depression or anxiety or a subgroup of either condition. Explicit exclusion criteria were used to assist the screening process. The rating procedure, number of raters involved and inter-rater agreement was not reported. Methods of review: Twelve studies met the final inclusion criteria. Means, standard deviations and sample size for the primary symptom measure and for measures of depression and anxiety were entered into Review Manager (RevMan) [Computer program]. Version 5.2. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2012. The review team then calculated the standardised mean difference (SMD: a measure of ‘effect size’) where possible. Post-intervention between group-effect sizes were calculated using a random effects model; Hedges g was used to calculate the effect size for each study. The Jadad scale was used to independently assess the methodological quality of RCTs. Results: Twelve studies (578 participants) met the final inclusion criteria. The Jadadrating scale was used to evaluate the quality of the included studies. Between group benefits of MBI relative to control conditions on primary symptom severity were significant (Hedges g = 0.59, 95% CI = 0.12 to 1.06). MBI was effective in reducing depressive symptom severity (Hedges g = 0.73, 95% CI = 0.09 to 1.36), but not anxiety symptom severity (Hedges g = 0.55, 95% CI = 0.09 to 1.18, when there was an inactive control (Hedges g = 1.03, 95% CI = 0.40 to 1.66), but not an active control (Hedges g = 0.03, 95% CI = 0.54 to 0.48). MBCT were found to be effective (Hedges g = 0.39, 95% CI = 0.15 to 0.63), but not MBSR (Hedges g = 0.75, 95% CI = 0.31 to 1.81). Author’s conclusions: MBIs used with people experiencing acute episodes of depression provide significant benefits to reducing primary symptom severity. MBIs may also produce similar patient outcomes as group cognitive behavioural therapy and may offer people experiencing depression with a secondary therapy option. The findings also suggest there is limited evidence to support the use of MBIs in reducing the symptoms of acute episodes of anxiety. Contact details of original author: Clara Strauss: c.y. strauss@sussex.ac. uk