Impairment of an event-related potential correlate of memory in schizophrenia: effects of immediate and delayed word repetition

Objective: We investigated the nature of the memory impairment in schizophr enia using an event-related potential (ERP). Methods: Visual ERPs were recorded while 20 schizophrenics and 20 controls performed semantic categorization tasks with incidental word repetitions. P articipants responded to occasional target words. Half of the non-target wo rds were repeated immediately after initial presentation (lag 0) or after 5 intervening words (lag 5). Results: In both groups. ERPs to words at lag 0 were more positive than tho se to non-repeated words, though this positive-going effect was attenuated in the schizophrenics, especially around 400-500 ms. The effect at lag 5 wa s smaller and shorter than that at lag 0 but was comparable between groups. Attenuation of the N400 peak occurred for word repetition at lag 0 in cont rols but not in schizophrenics, whereas a peak increment in the late positi ve component induced by word repetition at both lags was observed in both g roups. Conclusions: Findings indicate that patients with schizophrenia have a defi cit in a brain process modulating ERP correlates of memory, when words are repeated immediately. This deficit might be related to an abnormal N400 pri ming effect in schizophrenia. (C) 2001 Elsevier Science Ireland Ltd. All ri ghts reserved.