The Pattern of Neurocognitive Deficits in Patients with Schizophrenia

Chang, Ho Kyun; Kim, Eun Kyoung; Yi, Ho Taek; Paek, Ju Hee; Lee, Sang Yeon; Park, Byoung Kwan

Abstract

OBJECTIVES: Schizophrenic patients have been reported to be associated with abnormal performance on a broad range of neuropsychological tests. But it has been a persistent controversy in the neuropsychology of schizophrenia whether this disorder is characterized by generalized deficits or specific deficits. The purpose of this study was to investigate, using standardized Benton Neuropsychological Assessment(BNA), whether the specific pattern of neurocognitive deficits is found in schizophrenics.
METHODS
The subjects were composed of (1) 30 schizophrenic inpatients who were diagnosed as paranoid subtype according to DSM-IV diagnostic criterior and (2) 30 normal subjects with matching demographic variables(i.e. age, sex, educational level). All tests of BNA were given to schizophrenic patients and normal subjects, and the performances of schizophrenic patients and normal subjects were compared on all aspects of BNA. Schizophrenic symptoms were assessed via Positive and Negative Syndrome Scale(PANSS) to determine the relationship between clinical symptoms and schizophrenic cognitive deficits.
RESULTS
Of 12 tests of BNA, schizophrenic patients' performances on Serial Digit Learning(SDL), Facial Recognition Test(FR), Tactile Form Perception(TFP), Finger Localization(FL) were significantly lower than those of normal subjects. In addition, schizophrenic patients showed significantly lower performances than those of normal subjects on Right Hand, Left Hand, Identification of two simultaneously touched fingers of FL, and more Peripheral Error on Visual Form Perception Test(VFPT). Finally, no significant correlation was found with respect to the relationships between total scores, positive symptom scores, negative symptom scores of PANSS, and all scores of BNA tests in schizophrenic patients.
CONCLUSION
These results suggest that schizophrenic patients may have a specific pattern of neurocognitive deficits in verbal working memory, learning, attention, and complex sensory information processing in visual and haptic modality such as facial perception skills, tactile information processing, independent of psychotic symptoms. The pattern of deifcits is at least in partial, in agreement with many previous study results. On the tests of linguistic functions, visuospatial perception, and constructional abilities, schizophrenic patients' performances were not significantly different from those of normal subjects. The findings on visuospatial perception and constructional abilities imply that some posterior cortical zones may be relatively uncompromised in schizophrenia. Both poor performances on object recognition tests relative to normal performances on object location tests and verbal working memory dysfunction may be associated with the putative dysfunction of the reciprocal connections either (1) between the prefrontal and parietal cortex or (2) between the prefrontal cortex and hippocampal formation. This tentative explanation remains to be confirmed.