IntroductionNovel, evidence-based treatments are required for treatment-resistant post-traumatic stress disorder (PTSD). 3,4-Methylenedioxymethamphetamine (MDMA) has beneficially augmented psychotherapy in several small clinical trials.ObjectivesTo review the use of MDMA-assisted psychotherapy in treatment-resistant PTSD.MethodsSystematic searches of four databases were conducted from inception to February 2020. A meta-analysis was performed on trials which were double-blinded, randomised, and compared MDMA-assisted psychotherapy to psychotherapy and placebo. The primary outcomes were the differences in Clinician Administered PTSD Scale (CAPS-IV) score and Beck’s Depression Inventory (BDI). Secondary outcome measures included neurocognitive and physical adverse effects, at the time, and within seven days of intervention.ResultsFour randomised controlled trials (RCTs) met inclusion criteria. When compared to active placebo, intervention groups taking 75mg (MD -46.90; 95% CI -58.78, -35.02), 125mg (MD -20.98; 95% CI -34.35, -7.61) but not 100mg (MD -12.90; 95% CI -36.09, 10.29) of MDMA with psychotherapy, had significant decreases in CAPS-IV scores, as did the inactive placebo arm (MD -33.20; 95% CI -40.53, -25.87). A significant decrease in BDI when compared to active placebo (MD -10.80; 95% CI -20.39, -1.21) was only observed at 75mg. Compared to placebo, participants reported significantly more episodes of low mood, nausea and jaw-clenching during sessions and lack of appetite after seven days.ConclusionsThese results demonstrate potential therapeutic benefit with minimal physical and neurocognitive risk for the use of MDMA-assisted psychotherapy in TR-PTSD, despite little effect on Beck’s Depression Inventory. Better powered RCTs are required to investigate further.DisclosureJames Rucker has attended trial related meetings paid for by Compass Pathways Ltd.