A small study found that just two doses of magic mushrooms combined with therapy led to a decline in heavy drinking among the participants. People who received a placebo reduced their alcohol intake.

According to the researchers, by the end of the trial, almost half of those who received the drug stopped drinking completely.

The study is the latest in a cascade of research looking at the benefits of mind-altering compounds to treat a range of mental health problems.

The Food and Drug Administration is considering potential therapeutic uses for compounds like MDMA, also known as ecstasy, which are still illegal in the US.

According to Dr. Michael Bogenschutz, the findings offered hope for the 15 million Americans who struggle with excessive drinking. Over one hundred thousand people are killed each year by excessive alcohol use.

The results are exciting according to Dr. Bogenschutz. The effects of currently available treatments and medications tend to be small when it comes to alcohol use disorder.

A randomized trial followed 93 people for 32 weeks and divided them into two groups, one of which received a placebo and the other of which received a drug. The participants, all of whom struggled with excessive drinking, also took part in 12 therapy sessions that began several weeks before they received their first dose and continued for a month after the final dose. During the eight-hour sessions, participants' heart rate and blood pressure were monitored, as well as the dosage of the drug.

The study didn't show any serious adverse effects, but it did show that almost all the study subjects were able to guess whether or not they had received the drug. The authors wrote that the issue is still a challenge for clinical research.

ImageMary Beth Orr of Burien, Wash., used to have five or six drinks every evening and more on the weekends before enrolling in the psilocybin study.
Mary Beth Orr of Burien, Wash., used to have five or six drinks every evening and more on the weekends before enrolling in the psilocybin study.Credit...Ted S. Warren/Associated Press
Mary Beth Orr of Burien, Wash., used to have five or six drinks every evening and more on the weekends before enrolling in the psilocybin study.

One of the study participants who received the drug said it helped change her relationship with alcohol. Her life was diminished by nightly boozing that left her feeling miserable in the morning, even though she never blacked out and described herself as a "classy drinker".

She spent a lot of time thinking about not drinking in the evening. I tried to stop, but couldn't.

She said the sessions were unnerving but illuminating. She had an emotional encounter with her dead father on the mystical journeys. She said it was like a beautiful show with jewels and the sense of rushing through a tunnel with deity figures looking down at her. Two therapists helped her lay on a sofa while soothing music played in her headphones.

The second session was anchored by a conversation with a family member who she said had caused her immense pain over the years. She wished the relative well and kissed him goodbye.

She said that the message was forgiveness, understanding and love for everyone. She said that she is no longer afraid of feelings.

After three years after her last session, Ms. Orr said that she rarely drinks but occasionally sips wine. It's not that I watch my drinking, it's just that I don't think about it.

Scientists don't fully understand how the mind works, but the drugs are thought to promote a rewiring of the brain, which can help people with mental illnesses.

Dr. Matthew W. Johnson, who was not involved in the study, said he was encouraged by the results because they were large and double blind. He pointed out that a previous trial had just 10 participants.

Dr. Johnson is a professor of Psychiatry and Behavioral Sciences and is conducting a study on the use of psilocybin for Smoking Cessation.

The current crop of anti-addiction therapies, most of which take aim at the cravings, withdrawal or drug-mediated reward receptors in the brain, is exciting, according to him. According to Dr. Johnson, the psychological underpinning of addiction appears to be affected by the effects of the drugs.

He said that it's rare for a potential medication to be effective for multiple forms of addiction.

A second trial would include more than 200 people and test the effectiveness of a single dose of the drug. A different placebo will be used in the trial.

The trial was approved by the F.D.A. on Monday and will be the largest to date.