Effects of pimozide on cognition in children with Tourette syndrome: interaction with comorbid attention deficit hyperactivity disorder.

Pimozide, a dopamine receptor antagonist, dopamine uptake inhibitor and L-type calcium channel blocker, is used in children suffering from Tourette syndrome (TS), but its effect on frequently comorbid attention deficit hyperactivity disorder (ADHD) is unknown. We have characterized the cognitive effects of pimozide and haloperidol in TS in relation to comorbid ADHD. Sixty-six consecutive outpatients with TS (DSM-III-R), ages 7-16, were randomly assigned to pimozide, haloperidol or medication-free clinical treatment and evaluated cognitively after 6 weeks. Continuous performance task (CPT) and memory search efficiency were compared across treatments. Treatment, comorbid ADHD and their interaction were significant on the CPT task. Pimozide treatment was superior to haloperidol and improved memory search efficiently over the no-drug condition.