Abstract

This study investigated the cognitive impairment and neurophysiological mechanism of schizophrenia by event-related potential(ERP) and neuropsychological tests. The patient group showed significantly reduced P300 amplitude and prolonged P200, N200, P300 latency than control group. In terms of neuropsychological tests, schizophrenic patients showed impaired performance on tests evaluating problem-solving, verbal learning and verbal memory. The amplitude and latency of P200 and N200 were correlated with performance of Trail-Making Test(B) and Object Alternation Test(OAT), while the late cognitive peak, P300, was correlated with performance of Verbal learning Test(LNVLT) and Wisconsin Card Sorting Test(WCST). These results indicate that the schizophrenic patient has impairment of information-processing, and this impairment begins to emerge from the early stages of information-processing such as encoding, identification and classification of stimulus. P200 and N200 seem to be affected by subject's attention or mental flexibility, while P300 is associated with higher cognitive functions such as problem-solving, verbal learning and verbal memory. These results also indicate that schizophrenia is related to the structural or functional abnormalities of various cortical areas including frontal and temporal lobe rather than a circumscribed cortical area.