Medications used for the treatment of children with Tourette Syndrome are often limited in their effectiveness and may be associated with side effects. A medication known as tetrabenazine (soon to be available in the USA) is reported to be effective and well tolerated in the treatment of children with tics in open-label, non-blinded studies. Although tetrabenazine has been in clinical use for many years, controlled clinical trials with the drug on individuals with TS are limited. Tetrabenazine acts by depleting the supply of dopamine, norepinephrine, and serotonin in nerve terminals, thereby decreasing the amount available for release. Although the exact mechanism of action is not fully understood, depleting the brain of these neurotransmitters can help control the symptoms of some movement disorders. We propose to study tetrabenazine in a controlled, randomized, blinded trial of 50 children and adolescents with Tourette Syndrome. Subjects will be evaluated every two weeks throughout the study. During the first 8 weeks, children will be given either the study medication (tetrabenazine), or a placebo pill (a tablet containing no medication but similar in appearance to the study medication.) Over the next 9 weeks, all children, including those who took the placebo pill, will be given tetrabenazine, but at different doses. The effect of the tetrabenazine on tics and other associated conditions (ADHD and OCD) will be assessed. Potential side effects will be closely monitored. We anticipate that the main outcome will be an improvement in the symptom severity of the tic disorder. Mary Jenkins, M.D. FRCPC, University of Western Ontario, London, Ontario, Canada Samay Jain, M.D. University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania Award: $146,575 Tourette Association of America Inc. – Research Grant Award 2006-2007