Chronic, multiple tics of Gilles de la Tourette's disease. CSF acid monoamine metabolites after probenecid administration.

Central nervous system metabolism in six children and one adult with the syndrome of chronic multiple tics was studied by measuring the accumulation of acid metabolites of dopamine and serotonin (homovanillic acid [HVA] and 5-hydroxyindole-acetic acid [5-HIAA], respectively) in the CSF following probenecid administration. The accumulation of 5-HIAA was reduced in patients with multiple tics in contrast with other pediatric patients (N = 27). The degree of reduction in 5-HIAA relative to HVA appeared to be associated with the severity of the tic disorder. With dextroamphetamine, tic symptoms worsened, CSF HVA level decreased, and CSF 5-HIAA concentration increased. These findings suggest an association in Gilles de la Tourette's disease of reduced functioning of inhibitory serotonergic mechanisms and functional dopaminergic overactivity.