The P3 event-related potential in young recent-onset schizophrenic patients

In schizophrenic patients, the amplitude of the P3 event-related potential (ERP) is usually decreased and the latency is often prolonged. Most ERP studies have compared schizophrenic patients with chronic illness or in mixed age groups with age-matched control subjects. However, P3 latency and amplitude change with age, and P3 latency increases more rapidly in schizophrenic patients than in control subjects. To investigate whether mixed age groups and chronic illness have been determining 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 group compared with the control group. P3 latencies were less significantly prolonged in the schizophrenic group than in other studies. Furthermore, in an exploratory study, the ERPs resulting from application of 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 that a defect in inhibition of incoming sensory information in the nucleus reticularis thalami may play a role in the pathogenesis of schizophrenia. Such a defect could result in a dysfunctional filter function of external stimuli and may therefore affect the social and psychological functioning of the patient. (C) 1998 Rapid Science Ltd