Neuropsychologic deficits are prevalent among schizophrenic patients and are closely
associated with pathogenesis and outcome. The pattern, extent, severity and contributing
factors to such deficits remain to be examined in Taiwanese schizophrenic patients.
A total of 122 schizophrenic patients and 94 healthy subjects for comparison were
assessed by a comprehensive neuropsychologic test battery covering the eight cognitive
domains of verbal ability, visual spatial ability, abstraction/execution, verbal memory,
visual memory, perceptual/motor ability, mental control and attention. The relationships
among cognitive deficits, demographic characteristics, clinical historical variables
and clinical symptoms were further explored by multivariate regression analysis.
A pattern of selective deficits superimposed on a generalized deficit was found for
schizophrenic patients as a group. The mean overall deficit was 1.93 standard deviations
below the control mean, and abstraction/execution, verbal memory, visual memory and
attention were relatively impaired among the eight cognitive domains. However, there
was also marked heterogeneity in individual performances in that 24.2%, 46.2% and
29.5% of patients performed at within normal range, moderately impaired and severely
impaired levels, respectively. Duration of illness substantially affected the profile
and severity of the deficits, suggesting a progressive deteriorating course in neuropsychological
performance. The major predictors of cognitive deficits were number of formal years
of education achieved and concurrent severity of disorganization symptoms.
In a large sample of schizophrenic patients who underwent comprehensive neuropsychologic
evaluation, the current results confirmed that cognitive deficits were prevalent but
not a universal feature within schizophrenia. The selective impairment pattern also
confirmed that such deficits were mainly in frontal and frontotemporal related functions.
Despite evidence suggesting that disease chronicity entailed a decline in selective
cognitive domains, the trajectory of the neuropsychologic deficits remains to be examined
by further longitudinal studies.