Amplitude and area of the auditory P300 recorded with eyes open reflect remission of schizophrenia

Abstract

Schizophrenic patients reportedly demonstrate smaller P300 amplitudes, which have been related to cognitive deficits, as well as structural and chemical abnormalities (Ford et al 1994a; Pritchard 1986). Auditory P300 amplitude is known to be resistant to changes in neuroleptic medication or clinical state, so it has been deemed a candidate for a trait marker for vulnerability to schizophrenia (Blackwood et al 1987; Eikmeir et al 1992; Ford et al 1994a, 1994b; Pritchard 1986). Duncan et al (1987), however, have shown that the visual P300 ampiitude is negatively correlated with clinical improvement as measured by brief psychiatric rating scale (BPRS) scores. Thus they suggested that visual P300 amplitude may serve as a state marker in schizophrenia (Duncan et al 1987). We recorded serial sessions of auditory event-related potentials (ERPs) in schizophrenic patients during the course of their treatment for up to 6 months following admission. Since withinsession and between-session reliabilities of P300 measures recorded with eyes open are usually higher than those recorded with eyes closed (Maeda et al 1995), eyes-open and eyes-closed recordings were both made to provide further data regarding the long-term reliability of P300 recorded under these two sets of conditions. In addition, P300 area seems to be more reliable than P300 amplitude (Maeda et al 1995), so P300 area was measured as well.