Afterward, almost all of the participants experienced a significant reduction in anxiety and depression. Scientists checked in with the patients six months later; all reported that they still felt calmer and happier. Volunteer Gail Thomas told me that the treatment helped her overcome a deep sense of loneliness. “The main message from the trip was that we’re all connected,” she said. “We’re not alone.”

“The fact that a drug given once can have such an effect for so long is an unprecedented finding,” NYU psychiatrist Stephen Ross told the New Yorker. “We have never had anything like it in the psychiatric field.”

Other researchers have tested the drug as a treatment for depression, addiction and other mental problems such as obsessive-compulsive disorder. Remarkably, in each small trial, scientists saw incredible results.