An event-related potential investigation of response inhibition in schizophrenia and psychopathy.
BACKGROUND
Schizophrenia and psychopathy are both characterized by impulsive, poorly planned behavior. This behavior may originate from a weak or poorly coordinated response inhibition system. We tested the hypothesis that schizophrenia and psychopathy are associated with abnormal neural processing during the suppression of inappropriate responses.


METHODS
The participants were schizophrenic patients, nonpsychotic psychopaths, and nonpsychotic, nonpsychopathic control subjects (defined by the Hare Psychopathy Checklist-Revised), all incarcerated in a maximum security psychiatric facility. We recorded behavioral responses and event-related potentials (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 participants showed greater frontal ERP negativity (N275) to the No Go stimuli than to the Go stimuli. This effect was small in the schizophrenic patients and absent in the psychopaths. For the nonpsychopaths, the P375 ERP component was larger on Go than on No Go trials, a difference that was absent in schizophrenic patients and in the opposite direction in psychopaths.


CONCLUSIONS
These findings support the hypothesis that the neural processes involved in response inhibition are abnormal in both schizophrenia and psychopathy; however, the nature of these processes appears to be different in the two disorders.
Kiehl
K A
KA
Department of Psychology, University of British Columbia, Vancouver, Canada.
Smith
A M
AM
Hare
R D
RD
Liddle
P F
PF
D000293:Adolescent; D000328:Adult; D000987:Antisocial Personality Disorder / Q000503:physiopathology* / Q000523:psychology; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005625:Frontal Lobe / Q000503:physiopathology*; D007839:Functional Laterality / Q000502:physiology; D006179:Gyrus Cinguli / Q000503:physiopathology*; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008875:Middle Aged; D011930:Reaction Time; D012559:Schizophrenia / Q000503:physiopathology*; D012565:Schizophrenic Psychology