ABSTRACT
OBJECTIVES: The purpose of this study is to examine whether the neurocognitive deficits of schizophrenia may be associated with certain features of symptomatology or a stable vulnerability of disease itself. METHOD: The 42 schizophrenic patients and 35 matched normal controls with sex, age, and education level were examined for their sustained attention, sensory register, executive function, concentration and attention, and verbal memory and learning in the acute and remitted stages of schizophrenia using Degraded Stimulus Continuous Performance Test, Span Apprehension Task, Wisconsin Card Sorting Test, Digit Span, and Rey Auditory Verbal Learning Test, respectively. RESULTS: The schizophrenic patients showed significant deficits in the sustained attention, sensory register, executive function, and verbal memory and learning compared with the normal controls in both acute and remitted stages of schizophrenia. Regarding the concentration and attention, the schizophrenic patients showed significant deficits in the backward digit span compared with the normal controls during acute stages, but there was no difference between two groups in the forward and backward digit span during remitted stages. No difference was evident in the sustained attention, sensory register, executive function, and verbal memory and learning between acute and remitted stages of schizophrenia. But the forward and backward digit span of schizophrenic patients showed significant improvement in the remitted stages compared with acute stages. CONCLUSIONS: The sustained attention and sensory register deficits in the visual information processing associated with schizophrenia, detected by high-processing-load version of the Degraded Stimulus Continuous Performance Test and Span Apprehension Task, are highly possible to be stable vulnerability indicators. Executive functioning deficit in the schizophrenic patients detected by Wisconsin Card Sorting Test is not likely to be dependent on symptoms, so it is difficult to conclude that it is a stable vulnerability indicators of schizophrenia. In the digit span task, the forward digit span is more likely to be a episodic indicator but the backward digit span is likely to be a mediating vulnerability indicator. And the forward and backward digit span tasks seem to be tap different cognitive abilities that are differentially associated with the diathesis for schizophrenia. Some forms of the verbal memory and learning deficits associated with schizophrenia appear to be a stable vulnerability indicators.