Researchers performed a randomised, double-blind, dose-response, phase 2 trial at an outpatient psychiatric clinic in the USA, which included service personnel who were 18 years or older, with chronic PTSD duration of 6 months or more, and who had a Clinician-Administered PTSD Scale (CAPS-IV) total score of 50 or greater. They found that effective doses of MDMA that were administered in a controlled setting, along with adjunctive psychotherapy, were well tolerated and were effective at reducing the symptoms of post-traumatic stress disorder.