The American Medical Association stated in an online report "Medical Marijuana (A-01)" (accessed on Jan. 10, 2007):
"Only limited data exist on the effects of marijuana in patients with Tourette’s syndrome who respond inadequately to standard treatment, consisting of 4 case histories that report beneficial effects of smoked marijuana and 1 who reported substantial benefit from oral 9-THC (10 mg)."
The Institute of Medicine published in its Mar. 1999 report titled "Marijuana and Medicine: Assessing the Science Base":
"The movement disorders most often discussed as candidates for marijuana-based therapies are dystonias, Huntington's disease, Parkinson's disease and Tourette's syndrome.
As a general consideration, it is important to note that stress and anxiety tend to worsen the symptoms of movement disorders. Thus, marijuana's calming effect could be a primary reason why some patients claim that it brings them relief."
Kirsten R. Müller-Vahl, MD, Director of the Tourette Syndrome Clinic at the Medical School of Hannover, stated in her Oct. 2003 article "Cannabinoids Reduce Symptoms of Tourette's Syndrome," published in Expert Opinion on Pharmacology:
"Currently, the treatment of Tourette's syndrome (TS) is unsatisfactory. Therefore, there is expanding interest in new therapeutical strategies. Anecdotal reports suggested that the use of cannabis might improve not only tics, but also behavioural problems in patients with TS.
A single-dose, cross-over study in 12 patients, as well as a 6-week, randomised trial in 24 patients, demonstrated that delta-9-tetrahydrocannabinol (THC), the most psychoactive ingredient of cannabis, reduces tics in TS patients. No serious adverse effects occurred and no impairment on neuropsychological performance was observed. If well-established drugs either fail to improve tics or cause significant adverse effects, in adult patients, therapy with delta-9-THC should be tried.
At present, it remains unclear whether herbal cannabis, different natural or synthetic cannabinoid CB1-receptor agonists or agents that interfere with the inactivation of endocannabinoids, may have the best adverse effect profile in TS."
Reuven Sandyk, MD, Assistant to the Editor-in-Chief at the International Journal of Neuroscience, and Gavin Awerbuch, MD, a Neurologist and Pain Management/ Sleep Disorder Specialist, stated in their Dec., 1988 letter to the Journal of Clinical Psychopharmacology titled "Marijuana and Tourette's Syndrome":
"We recently encountered three patients with TS [Tourette's syndrome] who experienced incomplete responses to conventional anti-TS drugs but noted a significant amelioration of symptoms when smoking marijuana...
It is reasonable to assume that the effects of marijuana in TS may be largely related to its anxiety-reducing properties, although a more specific antidyskinetic effect cannot be excluded."