Mindfulness-based school interventions: A systematic review of outcome evidence quality by study design.

Objective: The purpose of this systematic review was to assess the current literature on mindfulness-based school interventions (MBSIs) by evaluating evidence across specific outcomes for youth. Methods: We evaluated 77 studies with a total sample of 12,358 students across five continents, assessing the quality of each study through a robust coding system for evidence-based guidelines. Coders rated each study numerically per study design as 1++ (RCT with a very low risk of bias) to 4 (expert opinion) and across studies for the corresponding evidence letter grade, from highest quality ('A Grade') to lowest quality ('D Grade') evidence. Results: The highest quality evidence ('A Grade') across outcomes indicated that MBSIs increased prosocial behavior, resilience, executive function, attention and mindfulness, and decreased anxiety, attention problems/ADHD behaviors and conduct behaviors. The highest quality evidence for well-being was split, with some studies showing increased well-being and some showing no improvements. The highest quality evidence suggests MBSIs have a null effect on depression symptoms. Conclusion: This review demonstrates the promise of incorporating mindfulness interventions in school settings for improving certain youth outcomes. We urge researchers interested in MBSIs to study their effectiveness using more rigorous designs (e.g., RCTs with active control groups, multi-method outcome assessment, and follow-up evaluation), to minimize bias and promote higher quality-not just increased quantity-evidence that can be relied upon to guide school-based practice.