Psychological Medicine

Original Articles

Neuropsychological evidence for frontostriatal dysfunction in schizophrenia

R. Elliotta1, P. J. McKennaa1, T. W. Robbinsa1 and B. J. Sahakiana1 c1

a1 Departments of Experimental Psychology and Psychiatry, University of Cambridge and Fulbourn Hospital, Cambridge

SYNOPSIS

Schizophrenics and controls were compared on a computerized test of attentional set-shifting which provides a componential analysis of the Wisconsin Card Sort Test and has previously been shown to be sensitive to frontal lobe dysfunction and Parkinson's disease. The main test was of extra-dimensional shifting where subjects are required to shift reponse to an alternative perceptual dimension. In one condition, termed ‘perseveration’, subjects are required to shift to a novel dimension and ignore the previously relevant one. In the other condition, termed ‘learned irrelevance’, subjects are required to shift to the previously irrelevant dimension and ignore a novel one. Chronic medicated schizophrenics (N = 32) show a highly significant impairment on the perseveration but not the learned irrelevance condition, as compared to normal age and IQ matched controls (N = 24). This was true even of a subgroup of patients with preserved IQ. The impairments in attentional set-shifting failed to correlate with patients' scores on the Mini-Mental State Examination (mean; S.D. 26·8; 1·8) or with scores on a test of recognition memory. These results provide evidence for a specific deficit in a set-shifting test of executive function and support a hypothesis of frontostriatal dysfunction in schizophrenia.

Correspondence:

c1 Address for correspondence: Dr Barbara J. Sahakian, Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ.

Metrics