Neuropsychological correlates of N400 anomalies in patients with schizophrenia: A preliminary report

We investigated N400 anomalies and their relationship with neuropsychological disturbance of schizophrenia. Twelve patients with schizophrenia and 12 normal controls, matched for age, sex, education and handedness underwent both the neuropsychological test and the electrophysiological recordings employing semantic violation sentence paradigm. The patients with schizophrenia showed a reduced N400 amplitude and worse performance in the frontal lobe function test compared to healthy participants. Furthermore, statistically significant positive correlations were found between N400 amplitude and neuropsychological performances on the Stroop Task and Wisconsin Card Sorting Test in patients with schizophrenia. Our results suggest the possibility that N400 anomalies reflect the disturbed integrity of the fronto-temporal network in schizophrenia evidenced by neuropsychological deficits. In addition, we concluded that the N400 amplitude is a candidate for an endophenotype marker of schizophrenia by revealing its relationship to neuropsychological deficits.