Brain event-related potentials (ERPs) in schizophrenia during a word recognition memory task

Impairments of recognition memory for. words and attenuation of the ERP 'ol d-new' effect have been found in patients with left medial temporal lobe da mage. If left temporal lobe dysfunction in schizophrenia involves medial st ructures (e.g. hippocampus), then schizophrenic patients might show similar abnormalities of verbal recognition memory. This study recorded ERPs from 30 electrode sites while subjects were engaged in a continuous word recogni tion memory task. Results are reported for 24 patients having a diagnosis o f schizophrenia (n = 16) or schizoaffective disorder (n = 8) and 19 age-mat ched healthy controls. Both patients and controls showed the expected 'old- new' effect, with greater late positivity to correctly recognized old words at posterior sites, and there was also no significant difference between g roups in P3 amplitude. However, accuracy of word recognition memory was poo rer in patients than controls, and patients showed markedly smaller N2 ampl itude. Reduced amplitudes of N2 and N2-P3 were associated with poorer perfo rmance, with highest correlations over the left inferior parietal (N2) and left medial parietal (N2-P3) region. Moreover, patients failed to show sign ificantly greater left than right hemisphere amplitude of N2-P3 at posterio r sites, which was seen for healthy controls. These findings suggest that i mpaired word recognition in schizophrenia may arise from a left lateralized deficit at an early stage of processing, beginning at 200-300 ms after wor d onset. (C) 1999 Elsevier Science B.V. All rights reserved.