A more recent, more comprehensive study took place in 2003. In that study, Tourette's Syndrome patients were given either THC or placebo for six weeks, and asked to track their daily tics. Patients taking THC showed a significant decrease in tics, with no adverse effects, or negative effects on verbal memory, recall, or learning abilities. In a paper published in the Journal of Clinical Psychiatry, the researchers' conclusion was that "Therapy with delta-9 THC should be tried…" at least for adult patients.
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