NORMALIZATION OF AUDITORY PHYSIOLOGY BY CIGARETTE-SMOKING IN SCHIZOPHRENIC-PATIENTS

Objective: Because many schizophrenic patients are heavy smokers, it h as been suggested that nicotine normalizes some neuronal deficit invol ved in their illness. Schizophrenic subjects have various difficulties with maintenance of attention and selective processing of sensory inf ormation. One defect in sensory gating in schizophrenia has been chara cterized by recording auditory evoked potentials. Most normal subjects have a decrease in the evoked response to the second of two closely p aired stimuli, whereas most schizophrenic subjects do not. The aim of this study was to determine whether smoking normalizes this deficit in auditory sensory gating in schizophrenia. Method: Changes in auditory sensory gating in response to smoking cigarettes were studied in 1 0 smokers without psychiatric illness and 1 0 schizophrenic smokers. Bot h groups were asked to abstain from smoking from 11:00 p.m. until 8:00 a.m. the next morning, when their auditory evoked responses to pairs of clicks were recorded. The ability to gate sensory information is re flected in a decrease in the P50 wave amplitude in response to the sec ond of the two stimuli. After baseline recordings, the subjects smoked as much as they wished, and then two postsmoking recordings were perf ormed. Results: The schizophrenic patients bad a marked but brief impr ovement in P50 auditory gating immediately after smoking, whereas P50 gating for the normal smokers was slightly impaired. Conclusions: This study suggests that cigarette smoking can transiently normalize the i mpairment of auditory sensory gating in schizophrenic patients.