Scientists from Norway have pooled and re-analyzed data from old trials that tested lysergic acid diethylamide (LSD) for the treatment of alcoholism and concluded that a single dose of the psychedelic drug was effective in decreasing alcohol misuse. They report their findings in the early online 8 March issue of the Journal of Psychopharmacology.

From the 1950s to the 1970s, many research centres worldwide conducted trials to investigate how well LSD might treat a range of disorders, including alcohol addiction. In the 1970s though, it became increasingly difficult to conduct clinical trials: and by then the drug had been banned for non-medical use. Also, despite some promising results, the view was LSD had not demonstrated any medical benefits.

Not all the experiments would meet today’s standards for scientific rigour, but some might. The authors of this new study, Teri Krebs and Pål-Ørjan Johansen, researchers currently affiliated to the Department of Neuroscience at the Norwegian University of Science and Technology (NTNU), suggest the reason that medical interest in LSD gradually waned was probably while the earliest studies showed promising results, they also had design problems.

“Many scientists expected unrealistically good results from a single dose, and tended to ignore effects that lasted less than a year. Importantly, many of the individual studies did not have enough patients to reach a conclusion by themselves,” they write.

So they took a closer look at six published experiments that they regarded as having scientifically sound methodology and put them through a rigorous quantitative meta-analysis. Those trials had randomly assigned patients to receive either LSD or a comparison treatment.

Between them, the six studies totalled 536 volunteer patients, mostly men, who were all receiving alcoholism treatment. The trials had taken place in the US or Canada between 1966 and 1970.

This is the first time a rigorous meta-analysis has been conducted on this data. A meta-analysis is a statistical method where data sets from several studies of compatible design are pooled and analyzed as if they came from one large study.

Krebs and Johansen conclude that their results unambiguously show that LSD helped patients heavily addicted to alcohol and made it less likely they would relapse: “a single dose of LSD had a positive treatment effect that lasted at least six months”, they write.

“There has long been a need for better treatments for addiction. We think it is time to look at the use of psychedelics in treating various conditions,” they urge.

The authors say they don’t know how LSD works to treat alcohol addiction. They explain that we know the drug is non-toxic and non-addictive, and that it has a “striking effect on the imagination, perception and memories”.

And we know that it interacts with a particular serotonin receptor in the brain. Perhaps it stimulates the “formation of new connections and patterns”, thereby creating an “awareness of new perspectives and opportunities for action,” they speculate.

In all six of the trials included in the meta-analysis, the patients underwent the same treatment programme. But on one day of the programme, some patients received a large single dose of LSD, while the controls received a low dose of LSD, or a stimulant drug, or nothing.

The trials were double-blinded: neither the patients nor the drug administrators knew who would receive the full dose of LSD.

In all of the studies, the patients were encouraged to reflect on their alcoholism. In some of the trials, patients had the opportunity to talk with a therapist; in others, they received brief reassurance, if they wanted it.

All the trials carried out independent and standardized follow-up exams, between one to twelve months later.

In all of the studies, the results showed that the patients who received the full LSD dose fared the best.

“On average, 59% of full-dose patients showed a clear improvement compared with 38% in the other groups,” say the authors.

The patients who received the LSD dose were less likely to relapse into problematic alcohol use, and were more likely to abstain altogether.

The greatest improvements were during the first few months of treatment. This wore off with time. Perhaps this suggests repeated doses might work better.

“It is unusual for psychiatric drugs to have an effect that lasts for several months after a single dose, ” write the authors.

“We now better understand that alcoholism is a chronic, relapsing disorder that typically requires ongoing treatment. The next step should be to periodically provide additional doses of LSD in combination with modern evidence-based treatment programs,” they conclude.

The Research Council of Norway financed the study which was conducted during a research stay at Harvard Medical School.

Written by Catharine Paddock PhD