Impaired P600 in neuroleptic naive patients with first-episode schizophrenia

Deficits of working memory (WM) are recognized as an important pathological feature in schizophrenia. Since the P600 component of event related potent ials has been hypothesized that represents aspects of second-pass parsing p rocesses of information processing, and is related to WM, the present study focuses on P600 elicited during a WM test in drug-naive first-episode schi zophrenics (FES) compared to healthy controls. We examined 16 drug-naive fi rst-episode schizophrenic patients and 23 healthy controls matched for age and sex. Compared with controls schizophrenic patients showed reduced P600 amplitude on left temporoparietal region and increased P600 amplitude on le ft occipital region. With regard to the latency, the patients exhibited sig nificantly prolongation on right temporoparietal region. The obtained patte rn of differences classified correctly 89.20% of patients. Memory performan ce of patients was also significantly impaired relative to controls. Our re sults suggest that second-pass parsing process of information processing, a s indexed by P600, elicited during a WM test, is impaired in FES. Moreover, these findings lend support to the view that the auditory WM in schizophre nia involves or affects a circuitry including temporoparietal and occipital brain areas. NeuroReport 12:2801-2806 (C) 2001 Lippincott Williams & Wilki ns.