Biomarker levels will be analyzed to determine if MDMA-assisted therapy causes changes in these modulators of social behavior in this population as previously demonstrated in typically developing adults. Biomarker levels will be analyzed for persisting effects at one month and 6 months after treatment. Blood samples will be obtained from all subjects to measure plasma OT, AVP and CORT, which will be used to explore as potential surrogate endpoints at baseline, two hours after drug administration during the second experimental session, one month after the second experimental session, and at 6-month follow-up.