MDMA-Assisted Therapy Randomized Controlled Trial Incremental Effects Systematic Review and Meta-Analysis

Mental illness poses a substantial global burden, yet existing psychotherapies and psychopharmacologies often produce limited outcomes. Psychedelic-assisted therapies have re-emerged as potential transdiagnostic interventions. In particular, 3,4-methylenedioxymethamphetamine–assisted therapy (MDMA-AT) has generated interest for its rapid psychological effects and potential to enhance psychotherapy outcomes. However, the incremental efficacy of MDMA-AT relative to control interventions across transdiagnostic outcomes remains unclear. Further, there have been emerging concerns regarding harm reporting quality in MDMA-AT clinical trials. We conducted a systematic review and meta-analysis of MDMA-AT randomized controlled trials. Eleven publications representing eight controlled trials with 10 analyzed subgroups ( n = 295 participants) were included in meta-analyses. Two additional secondary publications were included for harm reporting syntheses ( k = 13 total). Across 114 extracted effect sizes, MDMA-AT demonstrated a significant moderate-to-large incremental reduction in psychopathology relative to controls (g = 1.03, 95% CI [0.46, 1.60]), though heterogeneity was high (I² = 76%). Incremental effects were larger versus inert placebos (g = 1.27) than active controls (g = 0.75). Symptom-specific analyses indicated strong incremental effects for trauma reduction (g=1.46 [95% CI: 0.67, 2.25]) and smaller non-significant effects for depression (g=0.51 [95% CI: −0.06, 1.08]). Harm reporting quality synthesis showed only 23% of publications met high-quality reporting standards. Overall, MDMA-AT demonstrates potential transdiagnostic efficacy, but small samples, confounding factors, and mediocre harm reporting highlight the need for larger more transparent clinical trials.