My colleagues and I recently showed that when adults with Tourette syndrome (TS) do certain memory tests, they “turn on” certain areas of the brain more than control subjects without TS. This change occurs despite the fact that the TS group performs as well as the controls do. More importantly, this difference can be corrected by manipulating the brain’s dopamine system with levodopa; a natural substance that the brain converts into dopamine. This is exciting since we have known for some time that drugs that either boost or suppress dopamine function can reduce tics. There are two ways to explain these results. It could be that the TS brain incorrectly controls the making of dopamine. On the other hand, the dopamine-making system could be working fine, in which case the abnormality would be in the brain circuits that dopamine affects. After getting the same dose of levodopa, we can test this directly by measuring how much dopamine is made in the brains of people with and without TS. This TSA grant will help us begin to answer that question using positron emission tomography (PET scans) and a marker substance called [11C]raclopride. This research may clarify how it is that drugs that affect brain dopamine can reduce symptoms of TS. If so, the answers may suggest ways to design alternative treatments that would have more good effects and fewer bad effects. Kevin J. Black, M.D., Movement Disorders Center, Washington University School of Medicine, St. Louis, MO Award: $75,000 This award has been funded throught the generosity of the Ochsman Family Foundation Tourette Association of America Inc. – Research Grant Award 2003-2004