The first controlled LSD study in more than 40 years reveals the drug could be used to help people with terminal illnesses deal better with death.
The study, published in the Journal of nervous and Mental Disease, showed that 12 people who agreed to take the banned hallucinogenic drug during therapy sessions felt "significant reductions in anxiety" about their lives ending.
Most of the subjects involved in the study suffered from terminal cancer, and many died within a year of the trial. However, researchers said those who took LSD as a complement to talk therapy felt more at ease about death and continued to feel less anxiety about for a year after the trial ended.
"The study was a success in the sense that we did not have any noteworthy adverse effects," said Peter Gasser, a private practice psychiatrist in Solothurn, Switzerland. "All participants reported a personal benefit from the treatment, and the effects were stable over time."
"Their anxiety went down and stayed down," he told the New York Times.
The study was the first into the psychological effects of LSD since research into the drug was banned in 1966. Tests have previously examined if LSD could help tackle alcoholism, as well as anxiety and depression in people with advanced stage cancer.
During the study, eight subjects received a full 200-microgram of LSD before two talk sessions, while the remaining four received around one tenth of this amount. Eleven of the 12 subjects had not taken LSD prior to participating in the study.
During the 10-hour "trips", the patients who took the full amount were asked to talk about their terminal illnesses as well as childhood experiences.
One of those who took part in the study, named only as Peter, said: "My LSD experience brought back some lost emotions and ability to trust, lots of psychological insights, and a timeless moment when the universe didn't seem like a trap, but like a revelation of utter beauty."
He added: "I had what you would call a mystical experience, I guess, lasting for some time, and the major part was pure distress at all these memories I had successfully forgotten for decades.
"I remember feeling very cold for a long time. I was shivering, even though I was sweating. It was a mental coldness, I think, a memory of neglect."
Peter added it "surprised" him that he was describing these feelings to Gasser as he had never done so to anyone before.
"I didn't know I was talking away until Dr Gasser made me notice," he added.
After two months of weekly sessions, those who took the full dose of LSD saw an improvement of 20% on standard measures of anxiety, while those who took the smaller amount got worse. When those who had the lower dose switched to the full amount, their anxiety levels went down too and continued for stay lower for a year.
While the researchers admitted the size of the study is too small to be conclusive, they believe it shows the ability to conduct LSD-based trials in a safe environment should be continued.
"This study is historic and marks a rebirth of investigation into LSD-assisted psychotherapy," says Rick Doblin, executive director of Multidisciplinary Association for Psychedelic Studies (MAPS) , who sponsored the study.
"The positive results and evidence of safety clearly show why additional, larger studies are needed."