Phase II Study Finds That Psilocybin Plus Therapy Can Help Treat Depression Symptoms

New research out this week is the latest to show that psilocybin—the active ingredient in magic mushrooms—can be a viable treatment for depression. The randomized Phase II trial found that a single dose of psilocybin combined with therapy significantly reduced people’s depression symptoms when compared to placebo over a six-week period. Those on psilocybin also experienced greater improvements in their quality of life.

The study was published Thursday in the journal JAMA. It involved 104 adults diagnosed with at least moderate clinical depression. The volunteers were randomly assigned to either receive a single 25 milligram dose of psilocybin or niacin, in conjunction with several sessions of therapy. Niacin was chosen as a placebo since it can induce temporary physical sensations like flushed skin, making it harder for volunteers to know which group they belonged to. The therapy included a session on the day of dosing as well as “postdose integration sessions” where people were encouraged to talk about their experiences.

Both groups were tracked for 43 days, or just about six weeks. By the end of the study period, the researchers found that psilocybin combined with therapy was associated with “a rapid and sustained antidepressant effect.”

The group on psilocybin reported significantly lower levels of depression on average compared to placebo, based on a standard measurement scale. Any observed treatment response also seemed to last longer in those taking psilocybin. And the psilocybin group reported greater improvements in their daily functioning and overall quality of life. People on psilocybin did experience a greater rate of adverse events, but no serious events clearly linked to the treatment were documented, the authors say.

Phase II trials on their own can’t provide definitive evidence that a drug or treatment works as intended. However, studies continue to suggest that psilocybin-assisted therapy can be a realistic option for some people with depression. A similar Phase II trial published last November, for instance, found that people with treatment-resistant depression experienced a significant reduction in symptoms after taking a single large dose of psilocybin along with psychological support.

“These findings add to increasing evidence that psilocybin—when administered with psychological support—may hold promise as a novel intervention” for depression, the authors of this latest study wrote.

Based on these promising results, at least one group has launched a large-scale Phase III trial of psilocybin-assisted therapy this year. These trials, if positive, would provide the evidence needed for regulators to formally approve psilocybin for depression. Researchers elsewhere are studying psilocybin for other conditions like alcohol use disorder. There have also been local efforts in the U.S. to legalize psilocybin for medicinal use.