Testing a new (D1) dopamine blocking strategy to treat Tourette syndrome in children

What is it about?

Dopamine exerts its effects on the brain by interacting with receptor molecules--the locks to which dopamine is the key. There are two main types of dopamine receptors in the brain, cleverly named D1 and D2 receptors. (I'm ignoring some complexity here.) We know D2 blockers suppress tics, but they also can have problematic side effects. This study involves ecopipam, the first dopamine D1 receptor blocking drug tested in Tourette syndrome (TS). Adults with TS had improved in a previous open-label study with ecopipam, so a careful scientific test was the next step. This report describes the first randomized, placebo-controlled study of ecopipam, tested here in a sample of 40 children and adolescents with TS, age 7-17. When taking the active drug, patients' scores on a standard measure of tic severity (YGTSS total tic score) improved 3 to 4 points more than when they were taking a placebo (inactive pill). About half of patients on ecopipam were "much improved" or "very much improved," versus a quarter of patients on placebo. Also of great importance, side effects were similar in the two groups, including no evidence of weight gain. All investigators received salary support from Psyadon for conducting this clinical trial.

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Why is it important?

Fortunately there are a number of treatments for TS that have been proven to work better than a placebo, including behavior therapy approaches with no side effects and a range of medications. But none of them works for more than about half of the patients who try it. New treatments are very much needed. This trial suggests that a new kind of medication, a dopamine D1 antagonist, may be a useful addition to the set of treatments for tic disorders. In addition, this clinical research provides evidence that studying dopamine D1 circuitry may help us better understand tic disorders in the future.

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