Normalization of information processing deficits in schizophrenia with clozapine

Objective: The authors tested the hypothesis that the use of an atypical dr ug, clozapine, for patients with schizophrenia is related to less impairmen t in information processing deficits (assessed by prepulse inhibition of th e startle response) than is the use of typical antipsychotics. Method: Two groups of schizophrenic patients-receiving either clozapine or a ran ge of typical antipsychotics-we re tested for prepulse inhibition (a reduction in response to a startling stimulus, if preceded briefly by a weak, nonstartl ing stimulus; measured at prepulse-to-pulse intervals of 30 msec, 60 msec, and 120 msec) of the acoustic startle response and compared with a group of healthy volunteers. Results: Patients receiving typical antipsychotics sho wed less prepulse inhibition with 30-msec and 60-msec prepulse trials than did comparison subjects. Clozapine-treated patients showed normal levels of prepulse inhibition. Conclusions: Clozapine is superior to typical antipsy chotics in normalizing prepulse inhibition, presumably because of its pharm acological effects on prefrontal regions of the brain or its effects on a b roader range of neuroreceptors.