Comorbid bipolar disorder in Tourette’s syndrome responds to the nicotinic receptor antagonist mecamylamine (Inversine)

Background: We have previously proposed that the therapeutic effect of transdermal nicotine in Tourette’s syndrome may involve nicotinic receptor inactivation resulting from a prolonged continuous exposure to nicotine. In vitro studies with nicotine and preliminary positive experience with mecamylamine (Inversine), a nicotinic receptor antagonist, in the clinical treatment of Tourette’s syndrome patients, further supports the receptor inactivation hypothesis. Methods: We retrospectively documented an unexpected therapeutic response to mecamylamine (2.5–7.5 mg/day) in two Tourette’s syndrome patients who were subsequently found to have comorbid bipolar disorder as defined by DSM-IV criteria. Results: In patient 1, the mood-stabilizing effect of mecamylamine was noticed by the patient during the course of mecamylamine treatment and brought to our attention, whereas for patient 2, manic symptoms were only apparent clinically following cessation of mecamylamine treatment. Conclusions: The clinical observations presented here suggest that nicotinic antagonists might be potential therapeutic agents for the treatment of bipolar disorder. Double-blind, placebo-controlled studies are now necessary to investigate these observations under more rigorous conditions.