Can mindfulness-based interventions reduce PTSD symptoms? An umbrella review.

Post-traumatic stress disorder (PTSD) is a debilitating, often chronic condition with substantial cross-national lifetime prevalence. Although mindfulness-based interventions (MBIs) may help reduce PTSD symptoms, efficacy results are inconsistent. Despite many systematic reviews (SRs) examining MBIs for PTSD, SR quality has been neither evaluated nor synthesized. We conducted an umbrella review to summarize and evaluate existing evidence regarding MBIs for PTSD, identifying 69 SRs (27 meta-analyses), consisting of 83 primary studies. Using AMSTAR2 (a valid SR quality assessment tool), we evaluated each SR on key domains relevant to methodological rigor and rated the confidence of inferences. Results found SRs were 65.2% non-rigorous, 27.5% likely rigorous, and 7.2% rigorous; common limitations included inadequate risk of bias assessment, extractions not completed in duplicate, and lack of pre-registration, highlighting the need for higher quality SRs. We then performed a meta-meta-analysis to estimate the efficacy of MBIs to reduce PTSD symptoms, yielding a medium effect size (SMD=0.41, p < .001), derived from 22 meta-analyses (with replicable data) and 35 unique articles. Analyses were consistent across control conditions and MBI type (first-generation/narrow [i.e., MBIs with well-established protocols]) versus broad (i.e., other MBI types), comparable with second-line treatments (e.g., pharmacotherapy). Findings were narratively synthesized; areas for methodological improvements in MBI research were identified.