LSD, the 1960s-era psychedelic drug that fuelled the early years of North American counterculture and hippies, is being recommended for further study as a treatment for severe alcohol abuse.

Researchers in Norway have completed a "meta-analysis" — a study of six other studies done between 1966 and 1970 — and concluded that "a single dose of LSD, in the context of various alcoholism treatment programs, is associated with a decrease in alcohol misuse."

The results were published online Thursday by the Journal of Psychopharmacology.

"It was not unusual for patients following their LSD experience to become much more self-accepting, to show greater openness and accessibility, and to adopt a more positive, optimistic view of their capacities to face future problems," a 1970 reported cited by the Norwegians said.

While a single large dose of lysergic acid diethylamide showed positive results in patient evaluations as long as six months later, the results weren't statistically significant at 12 months later.

The researchers at the Norwegian University of Science and Technology recommend further, more current studies of LSD's efficacy over longer periods of time. One of the earlier studies was done in Toronto in 1966 by the Alcoholism and Drug Addiction Research Foundation.

The Norwegian researchers searched through databases for studies done over the years of LSD and alcohol, then narrowed the field to six in the U.S. and Canada. They extracted the data, pooled it, and then in effect did their own study of the results.

"It is puzzling why this treatment approach has been largely overlooked," the Norwegian report said. In part, there may have been statistical and methodological reasons.

As well, "the complicated social and political history of LSD led to increasing difficulties in obtaining regulatory approval for clinical trials."

The effectiveness of a single dose of LSD, the Norway study said, compares well with the effectiveness of commonly prescribed alcohol-abuse medications such as naltrexone, acamprosate, or disulfiram.

"As an alternative to LSD, it may be worthwhile to evaluate shorter-acting psychedelics, such as mescaline, psilocybin, or dimethyltryptamine," the report said.