Clinical Studies and Case Reports

On this site you will find clinical studies with cannabis or single cannabinoids in different diseases and case reports on the use of cannabis by patients.
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TitleTreatment of Tourette's syndrome with delta-9-tetrahydrocannabinol.
Author(s)Muller-Vahl KR, Schneider U, Kolbe H, Emrich HM.
Journal, Volume, IssueAm J Psychiatry. 1999 Mar;156(3):495.
Major outcome(s)Improvement of tics and obsessive-compulsive behavior
IndicationTourette's syndromeAbstract


To the Editor: Tourette's syndrome is a complex neuropsychiatric disorder of unknown etiology. Earlier reports suggested beneficial effects in Tourette's syndrome when smoking marijuana (Cannabis sativa) (1, 2, 3). We report a successful treatment of Tourette's syndrome with delta-9-tetrahydrocannabinol (9-THC), the major psychoactive ingredient of marijuana.

Mr. A, a 25-year-old man, was diagnosed with attention deficit hyperactivity disorder at age 6. Motor and vocal tics started at age 10. During adolescence, he developed obsessive-compulsive behavior, anxiety, lack of impulse control, and self-injurious behavior. The diagnosis of Tourette's syndrome according to DSM-IV criteria was made at age 22. At age 19, he started smoking marijuana. When using 2–3 g/day, he noted a marked improvement of both vocal and motor tics and associated behavioral disorders. Therefore, he stopped less effective medical treatment with pimozide.
In an uncontrolled open clinical trial, we investigated whether 9-THC is effective in the therapy of Tourette's syndrome. Written informed consent was obtained from the patient after complete description of the study. The local ethics committee approved the study.

Mr. A was treated once with 10 mg of 9-THC. (He was unmedicated and had stopped smoking marijuana 3 days before.) Using the section on tic symptoms of the Tour­ette's Syndrome Global Scale, we found that Mr. A's total tic severity score was 41 before treatment and was reduced to 7 just 2 hours after treatment. Both motor and vocal tics improved and coprolalia disappeared. The improvement began 30 minutes after treatment and lasted for about 7 hours; no adverse effects occurred. To measure cognitive functions, we performed neuropsychological tests, which showed improved signal detection and sustained attention and reaction time after treatment. Mr. A himself noted an improvement of motor and vocal tics of about 70%. Furthermore, he felt an amelioration in attention, impulse control, obsessive-compulsive behavior, and premonitory feeling.

This is the first report of a successful treatment of Tourette's syndrome with 9-THC. Furthermore, for the first time, patients' subjective experiences when smoking marijuana were confirmed by using a valid and reliable rating scale and by excluding the fact of using an illegal drug. In addition, our findings give evidence that beneficial effects of marijuana may be due to the most psychoactive ingred­ient—9-THC. So far, it is unclear whether beneficial effects are caused by unspecific mechanisms like reduction of anxiety, sedation, or placebo effects. We hypothesize, however, that there may be an interaction between 9-THC and specific cannabinoid receptors located in basal ganglia (4). We are planning to confirm these preliminary results in a double-blind, placebo-controlled, crossover study.

Dose(s)10 mg
Duration (days)1
ParticipantsA man with Tourette's syndrome
DesignUncontrolled case report
Type of publicationMedical journal
Address of author(s)Abteilung für Klinische Psychiatrie und Psychotherapie, Medizinische Hochschule Hannover, Germany.
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