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The sustained attention to response task (SART), a measure of sustained attention created by Robertson, Manly, Andrade, Baddeley, and Yiend (1997), was administered to 51 patients with schizophrenia and 51 normal controls to provide information on the sensitivity of the measure in this clinical group. Patients with schizophrenia performed significantly worse than the normal controls in correct response, reaction time for correct response, and efficiency estimate of taking account of both the accuracy and speed of movement. Moreover, the patient group was more often correctly classified as defective on the basis of efficiency estimate than the normal controls. These data provide further evidence of the sensitivity of the SART to patients with schizophrenia.

Studies suggest that executive functions in patients with schizophrenia are markedly impaired as compared with normal controls. Most previous studies employed tests of executive functions adopted from frontal lobe neuropsychological paradigms based on lesion studies. This study employed several more recently developed theory-driven tests of executive functions addressing the construct of the supervisory attentional system. We explore the pattern of executive function impairment using factor analysis and subsequently investigate the relationships between these executive function factors and the clinical features in a sample of chronic schizophrenic patients. A total of 51 patients with chronic schizophrenia were recruited. The Sustained Attention Response to Task (SART), Six Elements Test (SET) and Hayling Sentence Completion Test (HSC) were used to assess executive functions. Three factors were identified within the executive function tests: 1) The "semantic inhibition factor" comprised items in the HSC, 2) the "action/attention inhibition" factor comprised the SART commission error and the SET rule-breaking score and 3) the "output generation factor" comprised the SET raw score and the correct SART response. Significant relationships were found between these derived factors and clinical features after partialling out the confounding effect of age, education and illness duration. The three theory-based tests of executive function were shown to have good construct validity among the group of chronic schizophrenic patients.

A double-blind comparison between benzodiazepines and neuroleptics was carried out for 1 1/2 years on 30 schizophrenics who had hitherto continuously received neuroleptics and remained apparently in full remission for at least 3-5 years. The benzodiazepine-group had a significantly higher relapse rate than the neuroleptic-group, meaning that we cannot stop neuroleptics for these patients yet. Three possible reasons for this are (1) demand of the natural course of the illness, (2) the fact that the patients agreed to stay in therapy for so long may signify a need for therapy, (3) some of the relapses on stopping neuroleptics may be 'withdrawal psychosis' after prolonged neuroleptic therapy. If withdrawal of neuroleptics is really needed, however, it may be considered for a subgroup of female patients whose illness started after the age of 40.