In a double-blind placebo-controlled study, both pimozide and
haloperidol significantly decreased tic frequency in nine patients with
Gilles de la Tourette's syndrome. These findings are consistent with the
catecholamine hypothesis of tic generation. Pimozide was associated with
significantly fewer complaints of lethargy. Follow-up 4-20 months later
showed that six of seven patients receiving pimozide and one of two
receiving haloperidol had had greater than 75% improvement in symptoms.