P300 reduction and prolongation with illness duration in schizophrenia

Background: The P300 component of the auditory event-related potential (ERP ) is both reduced in amplitude and delayed in schizophrenia. P300 is prolon ged and, less consistently, reduced with normal aging. Additional latency d elays are observed in neurodegenerative disorders. We asked whether P300 is reduced and delayed with longer illness duration in schizophrenia, consist ent with a neurodegenerative process. Methods: P300 amplitude and latency were recorded to infrequent auditory ta rget stimuli from 35 men with schizophrenia (DSM-III-R) and 26 control men. Effects of current age, age of onset, and duration of illness on P300 were assessed using regression analysis. Results: P300 amplitude showed no age-related decrease in either group; how ever, among schizophrenic participants, P300 amplitude correlated positivel y with onset age and negatively with illness duration. P300 latency correla ted positively with age in schizophrenic participants and also tended to in crease with age in controls. Slopes of the latency-age relationships were s ignificantly greater in schizophrenic participants than in control particip ants. Latency also correlated positively with illness duration but showed n o relationship to onset age. Conclusions: P300 amplitude and latency are reduced and delayed with longer illness duration in schizophrenia, consistent with a progressive pathophys iological process. Reduced P300 amplitude may also be a marker of an early onset variant of schizophrenia. (C) 2000 Society of Biological Psychiatry.