The drug is the active ingredient in so-called “magic mushrooms”.
The clinical trial to test the drug showed that two doses of psilocybin, along with talk therapy, aided people to decrease their drinking for at least eight months following their initial treatments.
The director of the NYU Langone Center for Psychedelic Medicine, Dr Michael Bogenschutz, told NBC News that “there’s really something going on here that has a lot of clinical potential if we can figure out how to harness it”.
The trial included 93 adults between the ages of 25 and 65. They received either psilocybin or antihistamine pills, which served as a placebo.
All of them took part in 12 therapy sessions. Before the trial, all of the participants consumed an average of seven drinks at a time.
The trial resulted in more than 80 per cent of those who received the psilocybin radically reducing their alcohol intake, compared to 50 per cent of those who received the antihistamine pills.
The results were published in JAMA Psychiatry on Wednesday.
By the end of the clinical trial, half of the psilocybin recipients had ceased drinking fully, while about a quarter of those given the antihistamine did so.
Recruiting for the trial organised by NYU Langone Health began in 2014 and included researchers from the University of Alabama at Birmingham and the University of New Mexico.
The results of the study come amid a global exploration of therapy assisted by psychedelics – such as ketamine and psilocybin – which is seen by some as a more effective way to treat addiction and mental health issues.
Dr Bogenschutz and the other researchers worked to discover if psilocybin alongside therapy could aid people to restrict their cravings and cut back on their drinking.
Johns Hopkins University psychiatry and behavioural sciences professor Matthew Johnson told NBC News that the results of the study are “really in line with accumulating evidence that psilocybin and other psychedelics that work in a very similar way in the brain can be effective in treating different types of addiction”.
Some participants said they had strong experiences or visions that changed their relationships with their addictions.
“Everyone’s experience is different,” Dr Bogenschutz said. “People’s brains appear to be able to kind of tailor the effects of the experience, depending on what they come to the situation with and what they need out of the experience.”
Assistant professor of psychiatry at Oregon Health & Science University, Dr Chris Stauffer, told NBC News that “the science shows that in virtually all the psilocybin-assisted psychotherapy trials for substance use disorders, greater mystical experience was associated with greater therapeutic change”.
“Ultimately, we don’t really know yet how this treatment works,” he added.
“This medication could be a game changer in the sense that these effects are larger than those of any existing treatment, and they persist after the treatment is done,” Dr Bogenschutz added.