Event-related potentials in drug-naive schizophrenic patients.

Decreased amplitudes of late components of event-related potentials (ERPs) in schizophrenia were ascribed to either psychotic features or to neuroleptic treatment of the patients. To rule out the drug effect, ERPs to stroboscopic stimuli were recorded in drug-naive schizophrenics and control subjects during no-task and simple-task sessions. Patients had significantly lower amplitudes of the late ERP components during both sessions, thus confirming similar results with treated schizophrenics. On the other hand, drug-naive patients did not differ from controls in the task-related relative facilitation of late ERP components. These results differ from findings of minimal ERP facilitation to task in treated schizophrenics. This discrepancy is discussed in the context of the effects of neuroleptic treatment and task demands on ERPs.