An event-related potential investigation of response inhibition in schizophrenia and psychopathy

Background: Schizophrenia and psychopathy are both characterized by impulsi ve, poorly planned behaviour. This behavior may originate from a weak or po orly coordinated response inhibition system. We tested the hypothesis that schizophrenia and psychopathy are associated with abnormal neural processin g during the suppression of inappropriate responses. Methods: The participants were schizophrenic patients, nonpsychotic psychop aths, and nonpsychotic, nonpsychopathic control subjects (defined by the Ha re psychopathy Checklist-Revised), all incarcerated in a maximum security p sychiatric facility. We recorded behavioural responses and event-related po tentials (ERPs) during a Go/No Go task. Results: Schizophrenic patients made more errors of commission than did the nonpsychopathic offenders. As expected, the nonpsychopathic nonpsychotic p articipants showed greater frontal ERP negativity (N275) to the No Go stimu li than to the Go stimuli. This effect was small in the schizophrenic patie nts and absent in the psychopaths. For the nonpsychopaths, the P375 ERP com ponent was larger on Go than on No Go trials,a difference that was absent i n schizophrenic patients an din the opposite direction in psychopaths. Conclusions: These findings support the hypothesis that the neural processe s involved in response inhibition are abnormal in both schizophrenia nad ps ychopathy; however, the nature of these processes appears to be different i n the two disorders. Biol Psychiatry 2000; 48:210-221 (C) 2000 Society of B iological Psychiatry.