The effectiveness of second-generation mindfulness interventions on anxiety and depression: A systematic review and meta-analysis.

Abstract

Second-generation mindfulness-based interventions (SG-MBIs), which integrate ethical and moral practices, have emerged as promising treatments for depressive and anxiety symptoms. This meta-analysis aims to evaluate the effectiveness of SG-MBIs in reducing depression and anxiety among adults. We conducted a meta-analysis of randomized controlled trials (RCTs) including adults from clinical populations, healthy adults, and mixed groups (e.g., individuals reporting psychological distress or physical health conditions without formal diagnoses). Databases searched included PubMed, Web of Science, and EBSCOhost (through April 2025). Effect sizes were computed using Hedges' g, calculated as the standardized mean differences between intervention and control groups at post-intervention, adjusted for small-sample bias, and synthesized under a random-effects model. Primary analyses focused on post-intervention outcomes, and additional analyses assessed long-term effects based on follow-up data from 20 trials (17 depression, 13 anxiety). In total, 43 studies on depression (n = 3756) and 37 studies on anxiety (n = 3199) were included. Moderator analyses tested participant type, control condition, intervention components, intervention type, primary outcome status and risk of bias status. SG-MBIs significantly reduced depressive (g = 0.59, 95 % CI [0.41, 0.78]) and anxiety symptoms (g = 0.61, 95 % CI [0.41, 0.81]); effects remained significant after outlier removal (depression: g = 0.44; anxiety: g = 0.40). Participant type significantly moderated outcomes, with clinical samples showing significantly larger improvements than both healthy and mixed samples. Intervention type also significantly moderated results. Control conditions, intervention components, outcome measures, primary outcome status, risk of bias status, and intervention duration were not significant moderators. Follow-up data (k = 20) indicated sustained depression reductions (g = 0.70). Most included trials were rated as having "some concerns" (n = 33), with 13 judged as low risk and 3 as high risk, suggesting that overall findings should be interpreted with caution. However, sensitivity analyses excluding these high-risk studies yielded similar results (depression: g = 0.61; anxiety: g = 0.64). SG-MBIs effectively reduce depression and anxiety and may be particularly valuable for clinical populations and self-compassion-focused interventions. Future research should aim for clearer operational definitions, standardized intervention protocols, exploration of wisdom-based components, and adequately powered RCTs to strengthen the evidence base and enhance clinical applicability.