Eye-blink rate in Tourette's syndrome

Gilles de la Tourette's syndrome is a hyperkinetic movement disorder in which an etiological role for dopaminergic hyperactivity has been proposed. Blink rate, a putative correlate of central dopamine activity, is commonly held to be elevated in Tourette's syndrome, a finding that would be consistent with the "dopamine" hypothesis of this disorder. In 19 patients who had Tourette's syndrome, however, blink rates during placebo treatment were identical with those of 49 index controls during reading and quiet sitting. Blink rate did correlate, however, with both the number and severity of tics. Pimozide treatment did not reduce blinking in the patients. It should be noted that nine of the patients were adolescents for whom there were not adequate age-matched controls, a fact which could obscure a blink rate elevation in this group. Insofar as blink rate is a putative correlate of central dopamine activity, these results are not consistent with elevated brain dopamine activity in adult patients who have Tourette's syndrome.