A new analysis of studies originally conducted in the 1960s suggests LSD may help people with alcoholism quit or reduce their drinking.

The new study combines the results of six trials that tested a single dose of LSD in 536 people with alcoholism. The researchers found 59 percent who took the drug either quit or significantly reduced their drinking, compared with 38 percent of participants who took a much smaller dose of LSD or used another treatment to prevent drinking, Time reports. Eight cases of adverse effects from LSD were reported; none lasted longer than the high itself, according to the article. The positive effect of LSD on drinking lasted at least six months, but was no longer apparent one year later.

Previous studies have suggested that LSD was not effective for alcoholism. The researchers of the new analysis said the earlier findings appear to be related to the fact that they did not include enough participants to show an effect.

“LSD had a significant beneficial effect on alcohol misuse at the first reported follow-up assessment,” the researchers wrote in the Journal of Psychopharmacology. “The effectiveness of a single dose of LSD compares well with the effectiveness of daily naltrexone [reVia, Vivitrol] acamprosate [Campral], or disulfiram [Antabuse].” Those drugs are approved by the Food and Drug Administration to treat alcoholism.

A number of hallucinogens and other illicit drugs are being studied as possible treatments for conditions including post-traumatic stress disorder, chronic pain, addiction and depression.