In dance clubs the drug called “ecstasy” is known as a potent (and illegal) way of enhancing your senses and boosting your mood. Now a study published online in July in the Journal of Psychopharmacology suggests that when coupled with psychotherapy, the drug might also be an effective treatment for post-traumatic stress disorder (PTSD).

South Carolina psychiatrist Michael Mithoefer, along with his co-therapist and wife, Annie Mithoefer, ran the trial with 21 participants who had developed chronic, treatment-resistant PTSD as a result of experiences with crime or war. They gave each participant two sessions with either MDMA (3,4-methylenedioxymeth­amph­­eta­­mine, which is ecstasy’s chemical name) or a placebo. Those who received MDMA took 125 milligrams, comparable to an amount a recreational user might take in a club, as their psychotherapy session began. Two and a half hours later, as the session progressed, subjects took a booster dose of half that amount to ensure the effects continued. The placebo group got sugar pills at corresponding times, and both groups received about eight hours of psychotherapy in total.

Two months after the treatment fewer than 17 percent of the MDMA-treated subjects continued to qualify for a diagnosis of PTSD, as opposed to 75 per­cent of the subjects who received a placebo. “Our results are encouraging, and we had no significant safety problems.

The next step is to find out if these results can be replicated elsewhere,” says Mithoefer, who is in private practice near Charleston. The study, sponsored by the Santa Cruz–based nonprofit Multidisciplinary Association for Psychedelic Studies, was the first FDA-approved trial evaluating MDMA’s therapeutic applications. More trials of ecstasy for PTSD are under way in Switzerland and Israel, with other studies starting soon in Canada, Jordan and Spain.

Mithoefer considers the findings especially notable given that 20 of the 21 participants had previously failed to obtain relief with currently approved medications and with at least one course of psychotherapy. PTSD is notoriously difficult to treat, affecting an estimated 7.8 percent of Americans.

So why does MDMA work when current medications do not? The leading theory, proposed by Mithoefer, builds on a therapeutic technique in which patients are exposed to their disturbing memories in a safe environment. To be effective, the theory goes, exposure therapy must be accompanied by a degree of emotional engagement, while avoiding dissociation or overwhelming emotion. PTSD patients often have a narrow window between thresholds of underarousal and overarousal. If MDMA widens this window, allowing patients to stay emotionally engaged while revisiting trau­matic experiences, then it may catalyze effective exposure therapy.

In addition, MDMA elevates the hormone oxytocin, which is involved in feelings of affiliation and trust. Higher levels of oxytocin might help patients to form a more trusting bond with their therapist, so that they may revisit traumatic experiences in an emotionally engaged state.