BERLIN (Reuters Health) - Chemicals found in cannabis can significantly reduce the symptoms of Tourette's syndrome, study findings suggest.

Dr. Kirsten Mueller-Vahl of the Hanover Medical College in Germany led a team that investigated the effects of chemicals called cannabinols in 12 adult Tourette's patients.

In the study, each patient was given a single oral dose of d9-THC--the most psychoactive chemical in cannabis--calculated based on their body weight, sex, age and prior use of marijuana, or a dose of inactive placebo. Symptoms were measured after the first treatment, and compared to symptoms after the same patient was switched to the other pill. Neither the patient nor the investigator knew whether they were given a placebo or the active treatment first.

A single dose of the cannabinol produced a significant reduction in symptoms for several hours compared to placebo, the researchers report in the April issue of Pharmacopsychiatry.

"The effects were clear," Mueller-Vahl told Reuters Health. "What was also interesting was that some patients experienced far greater effects than others. Some had a great effect, some only (a small effect), and a few none at all. But generally, the level of tic activity was reduced as were the compulsions, such as to shout, spit or swear."

Mueller-Vahl's team has also recently finished a 6-week long study with 24 patients.

Although the results are not yet published, the researcher said, "The second study supported what we had gathered from the initial one. Those taking the THC had significantly less tic behaviour."

Around 50,000 people in Germany alone have Tourette's syndrome, a complex neurological-psychiatric condition. Its cause remains unknown.

Current treatments are generally limited in effectiveness and often have considerable side effects. Mueller-Vahl said she wanted to see further research conducted on the potential medical uses of cannabis-based drugs.

"Marijuana and hashish from cannabis plants have been used as a medicine for centuries in various cultures," she said.

"In modern cultures, cannabis--because of its abusive use as a recreational drug and not least because of the long-unknown combination of chemicals--has until now barely played a role. There are around 80 different active chemicals in the cannabis plant," she noted.

"There is anecdotal evidence to suggest that the consumption of marijuana clearly and continuously benefits Tourette patients," Mueller-Vahl pointed out. "There is also a strong suggestion that the plant cannabis is more effective than synthetic THC, and that patients taking the mixture experience fewer unpleasant side effects."

She said the results opened up other potential areas of research. "The results prompt the question of how far the central cannabinoid receptor system of the brain plays a part in the origins of the condition," Mueller-Vahl noted. "The study should encourage further research into the effects of cannabis as well as some of the individual substances it contains, with other diseases too."

SOURCE: Pharmacopsychiatry 2002;33:57-61.

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