The controversial drug MDMA — also known as ecstasy — can help ease the effects of post-traumatic stress disorder, according to the first phase II clinical trial into the potential therapeutic benefits of using the drug as an adjunct to psychotherapy.

Most patients in the trial who were given psychotherapy along with doses of MDMA (3,4-methylenedioxy-N-methylamphetamine) experienced statistically significant reductions in the severity of their condition after two months, compared with a control group who received psychotherapy and a placebo. The results, which have yet to be submitted to a peer-reviewed scientific journal, were presented on 13 November at the International Society for Traumatic Stress Studies convention in Chicago, Illinois.

"It's important to realize this is a small pilot study and it will be necessary to replicate the results elsewhere," says Michael Mithoefer, a private-practice psychiatrist based in Mount Pleasant, South Carolina, who led the study, funded by the Multidisciplinary Association for Psychedelic Studies, an advocacy group based in California. "But it is evidence that this should be studied further," he adds.