The trial results, published Thursday (Sept. 4) in JAMA, include data from 194 people with moderate to severe anxiety across the U.S. The study compared these participants' responses to different doses of LSD against a placebo treatment. It found that the drug alleviated symptoms in many patients for at least three months after just one exposure.

That said, participants who were given low doses of LSD — either 25 or 50 micrograms — did not see a significant change in their symptoms. The effect kicked in only at higher doses — either 100 or 200 micrograms — and those given 100-microgram doses had the best results.

In fact, 12 weeks out from treatment, about 47% of the people who were given 100 micrograms were in remission, based on a standardized anxiety rating scale. And about 65% of the people in that group saw their scores on the scale fall by at least half. By comparison, only about 20% of the placebo group was in remission at the 12-week mark and about 30% saw their scores halved.