The Effects of Intensive Mindfulness Meditation Training on Mental Health: Evidence of Effectiveness and Safety from a Matched-Controlled Retreat Intervention Study

Objective: Despite growing popularity and scientific interest in meditation retreats, their effects on mental health and their safety remain poorly understood. Accordingly, we aimed to study their salutary and adverse effects on mental health. Method: We conducted a preregistered prospective intervention study among 89 adults who registered for 6-day insight mindfulness meditation retreats and 46 matched controls (Mage(SDage) = 33.75(9.50), 56.3% female). Controls were selected from a pool of 543 people recruited from the same community of meditators as retreat participants and matched to retreat participants on age and lifetime meditation experience. Participants completed measures of well-being (WHO-5), affect (I-PANAS-SF), emotion regulation (DERS-16), repetitive negative thinking (PTQ), brooding rumination (RRS-B), depression (PHQ-9), and anxiety (OASIS) at baseline and at 2-week follow-up. Results: Retreat participants demonstrated significant improvements in well-being, negative affect, perseverative thinking, brooding rumination, and depression symptoms at follow-up compared to matched controls (η² range = .04–.08, ps < .05). Importantly, the % of participants exhibiting statistically reliable deterioration in mental health outcomes were equal or lower among retreat participants than among matched controls in the entire sample, as well as in a sub-sample with clinically elevated depression and/or anxiety (ORs < 1). Conclusions: A 6-day mindfulness meditation retreat can produce mental health benefits on par with effect sizes of longer 8-week mindfulness-based programs. Findings challenge concerns about adverse effects of intensive high-dose meditation training and suggest that it may be a safe and effective intervention modality, even for clinically vulnerable adults struggling with depression and anxiety.