A single dose of the hallucinogenic drug LSD is an effective treatment for alcoholism - according to research led by a British doctor more than 40 years ago.

Studies on thousands of alcoholics treated with the drug in the early 1960s - before it became popular as a psychedelic street drug - showed it helped trigger a change in mental attitude leading drinkers to quit. But, in spite of its promise, the therapeutic potential of the drug has been ignored since it was banned worldwide in the late 1960s as a threat to public safety.

Now a historian who unearthed the research, led by British psychiatrist Humphrey Osmond and carried out in Canada, has interviewed the participants four decades on and says the results are dramatic.

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Erika Dyck, professor of the History of Medicine at the University of Alberta, said: "The LSD somehow gave these people experiences that psychologically took them outside of themselves and allowed them to see their own unhealthy behaviour more objectively, and then determine to change it.

"Even interviewing the patients 40 years after their experience, I was surprised at how loyal they were to the doctors who treated them, and how powerful they said the experience was for them - some even felt the experience saved their lives."

The research was carried out in Saskatchewan where Humphry Osmond and his fellow British psychiatrist John Smythies had gone after they became disillusioned with the state of psychiatric research in Britain.

They reasoned that a single large dose of LSD might have the same effect as experiencing delirium tremens which they had noted often marked the turning point in a drinker's career.

In one study, two-thirds of the alcoholics stopped drinking for at least 18 months after receiving one dose of LSD, compared to 25 per cent who stopped after group therapy and 12 per cent after individual therapy.

But the 1962 study was received with scepticism by a research group in Toronto. They repeated the study on blindfolded patients in isolation, and concluded that, under these conditions, LSD was not an effective treatment for alcoholism.

Writing in the journal Social History of Medicine, Dr Dyck said: "The LSD experience appeared to allow the patients to go through a spiritual journey that ultimately empowered them to heal themselves, and that's really quite an amazing therapy regimen. We accept all sorts of drugs, but I think LSD's 'street' popularity ultimately led to its demise. That's too bad because I think the researchers in Saskatchewan, among others, showed the drug is unique and has some intriguing properties that need to be explored further."

The ban on the use of LSD in medical experiments appears to be lifting, as researchers in the UShave recently been granted permission to conduct experiments. In Britain, some psychiatrists have been calling for research projects involving LSD and similar drugs to be re-started. The Royal College of Psychiatrists discussed the use of the drugs in treatment at its annual meeting in March, for the first time in over 30 years.

The story of Lysergic Acid Diethylamide

* LSD was first produced by Swiss chemist Dr Albert Hofmann in 1938 and studied for possible medicinal applications. Its psychedelic properties were not recognised until 1943, and it remained freely available to scientists until 1966.

* In 1953 and 1954, scientists working for MI6 administered LSD to servicemen without their consent in a bid to uncover a "truth drug". Earlier this year, the servicemen were paid thousands of pounds in compensation.

* Between 1950 and 1965, research on LSD and other hallucinogens generated more than 1,000 scientific papers, six international conferences, and was prescribed as treatment to more than 40,000 patients.

* In the late 1950s, film star Cary Grant was administered LSD on a therapeutic basis in an effort to overcome the problems behind his failed marriages. In 1961, Harvard psychology professor Dr Timothy Leary used a Harvard grant to give 3,500 doses to more than 400 volunteers. Of the test subjects, 90 per cent said they would like to repeat the experience while 62 per cent said it had changed their life for the better.

* In 1966, LSD was made illegal in Britain and subsequently adopted by the counter-culture movement of the late 1960s, who found spiritual and mystical qualities in the prolonged hallucinations, which typically lasted 8 to 15 hours.

* The spread of LSD among the general population followed its association with counter-culture icons such as Ken Kesey and his "acid tests", and Paul McCartney's highly publicised admission of use in a 1967 television interview.

* In composing "Tomorrow Never Knows", the song that signalled The Beatles' dalliance with the drug, John Lennon borrowed heavily from a 1964 book, The Psychedelic Experience, by Timothy Leary.

* Roger "Syd" Barrett of Pink Floyd was also a prolific user in the 1960s. An infamous clip of him on acid has received nearly 50,000 viewings on YouTube.

* In the late 1960s, a recreational dose typically amounted to one tenth of a grain of sand, or between 100 and 200 micrograms or "mics". Jim Morrison allegedly took 10,000 mics before performing with The Doors in 1966.

* But, according to the NHS, there is no evidence to suggest LSD does any long-term damage to the body or mind.

* Possession of LSD, a Class A drug, can get you up to seven years in jail. Supplying someone can get you life in prison and an unlimited fine.

Jeremy Clarke