THE P3 EVENT-RELATED POTENTIAL IN YOUNG RECENT-ONSET SCHIZOPHRENIC-PATIENTS

In schizophrenic patients, the amplitude of the P3 event-related poten tial (ERP) is usually decreased and the latency is often prolonged. Mo st ERP studies have compared schizophrenic patients with chronic illne ss or in mixed age groups with age-matched control subjects. However, P3 latency and amplitude change with age, and P3 latency increases mor e rapidly in schizophrenic patients than in control subjects. To inves tigate whether mixed age groups and chronic illness have been determin ing factors in ERP results, P3 was measured in 15 young patients (mean age 21.6 years) with recent-onset schizophrenia and compared with age -matched controls. P3 amplitudes were decreased in the schizophrenic g roup compared with the control group. P3 latencies were less significa ntly prolonged in the schizophrenic group than in other studies. Furth ermore, in an exploratory study, the ERPs resulting from application o f the irrelevant tones in some schizophrenic patients demonstrated ERP activity at latencies of 250-600 ms, while little or no activity was present at these latencies in control subjects. It is hypothesized tha t a defect in inhibition of incoming sensory information in the nucleu s reticularis thalami may play a role in the pathogenesis of schizophr enia. Such a defect could result in a dysfunctional filter function of external stimuli and may therefore affect the social and psychologica l functioning of the patient. (C) 1998 Rapid Science Ltd.