Treatment of tourette syndrome with delta-9-tetrahydrocannabinol (Δ9-THC): No influence on neuropsychological performance

Previous studies provide evidence that marijuana (Cannabis sativa)and delta-9-tetrahydrocannabinol(Δ9-THC), the major psychoactive ingredient of marijuana, respectively, are effective in the treatment of tics and behavioralproblems in Tourette syndrome (TS). It, therefore, has been speculated that the centralcannabinoid receptor system might be involved in TS pathology. However, in healthymarijuana users there is an ongoing debate as to whether the use of cannabis causes acute and/or long-term cognitive deficits. In thisrandomized double-blind placebo-controlled study, we investigated the effect of a treatment with up to 10 mg Δ9-THC over a 6-weekperiod on neuropsychologicalperformance in 24 patients suffering from TS. During medication and immediately as wellas 5-6 weeksafter withdrawalof Δ9-THC treatment, no detrimentaleffect was seen on learning curve, interference, recalland recognition of wordlists, immediate visualmemory span, and divided attention. Measuring immediate verbalmemory span, we even found a trend towards asignificant improvement during and after treatment. Results from this study corroborate previous data suggesting that in patients sufferingfrom TS, treatment with Δ9-THC causes neither acute nor long-term cognitive deficits. Larger and longer-duration controlled studies arerecommended to provide more information on the adverse effect profile of THC in patients suffering from TS. © 2003 Nature Publishing Group.