NICOTINE-HALOPERIDOL INTERACTIONS AND COGNITIVE PERFORMANCE IN SCHIZOPHRENICS

Nearly 90% of schizophrenics smoke cigarettes, considerably higher tha n the general population's rate of 25%. There is some indication that schizophrenics may smoke as a form of self-medication. Nicotine has a variety of pharmacologic effects that may both counteract some of the cognitive deficits of schizophrenia and counteract some of the adverse side effects of antipsychotic drugs. In the current study, we assesse d the interactions of haloperidol and nicotine on cognitive performanc e of a group of schizophrenics. These patients were in a double-blind study, randomly assigning them to low, moderate, and high dose levels of haloperidol. The subjects, all smokers, came to the laboratory on f our different mornings after overnight deprivation from cigarettes. In a double-blind fashion, they were administered placebo, low (7 mg/day ), medium (14 mg/day), or high (21 mg/day) dose nicotine skin patches. Three hours after administration of the skin patch, the subjects were given a computerized cognitive test battery including: simple reactio n time, complex reaction time (spatial rotation), delayed matching to sample, the Sternberg memory test, and the Conners continuous performa nce test (CPT). With the placebo nicotine patch, there was a haloperid ol dose-related impairment in delayed matching to sample choice accura cy and an increase in response time on the complex reaction time task. Nicotine caused a dose-related reversal of the haloperidol-induced im pairments in memory performance and complex reaction time. In the CPT, nicotine reduced the variability in response that is associated with attentional deficit. These results demonstrate the effects of nicotine in reversing some of the adverse side effects of haloperidol and impr oving cognitive performance in schizophrenia. (C) 1996 American Colleg e of Neuropsychopharmacology