Acts of control in schizophrenia: dissociating the components of inhibition.
BACKGROUND
Inhibitory deficits have been frequently reported in schizophrenia. Such deficits are usually associated with activities of prefrontal cortex and related networks. An understanding of intentional inhibitory control requires knowledge of how actions are planned and initiated and the components involved in stopping these actions.


METHODS
Patients with schizophrenia, a psychosis comparison group and a healthy control group participated in a visual choice reaction time (go) task and attempted to inhibit their responses to the go task when an auditory 'stop' signal was heard.


RESULTS
Schizophrenia patients demonstrated significantly slower response execution but the estimated speed of inhibition was not significantly different from that of healthy controls. Both patient groups were impaired in their ability to inhibit a response across a range of stop-signal delays. The poorer performance of schizophrenia patients only was related to a difficulty in reliably triggering the inhibitory response.


CONCLUSIONS
Impaired response inhibition is not unique to schizophrenia. However, the nature of their problem is markedly different from that of other psychopathological groups. Possible neural mechanisms underpinning difficulties in triggering inhibitory responses and in the voluntary initiation of actions in schizophrenia are considered.
Badcock
J C
JC
Department of Psychiatry and Behavioural Science, University of Western Australia/Centre for Clinical Research in Neuropsychiatry, Graylands Hospital, Claremont, WA.
Michie
P T
PT
Johnson
L
L
Combrinck
J
J
D000328:Adult; D001288:Attention / Q000502:physiology; D002755:Choice Behavior / Q000502:physiology; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D009483:Neuropsychological Tests; D010364:Pattern Recognition, Visual / Q000502:physiology; D017397:Prefrontal Cortex / Q000503:physiopathology; D011569:Psychiatric Status Rating Scales; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D012559:Schizophrenia / Q000175:diagnosis* / Q000503:physiopathology; D012565:Schizophrenic Psychology