Cognitive impairment in schizophrenia: specific relations to ventricular size and negative symptomatology.
A number of studies of schizophrenia have demonstrated associations between cognitive impairment and both cerebral ventricle size and negative symptomatology. The nature of these associations, however, have been obscured by interstudy differences in the assessment of cognitive functioning and by the lack of function-related specificity in measures of structural brain abnormality. In this study, 28 SCID-diagnosed chronic schizophrenic inpatients were administered a brief comprehensive battery of neuropsychological tests, a computed tomography (CT) scan, and were rated for positive and negative symptomatology. Enlarged ventricle-to-brain ratio (VBR) of the anterior portion of the lateral ventricles, the frontal horns, was found to be related to deficits in general intellectual level, conceptual thinking, immediate verbal memory, and psychomotor speed. VBR of the more usually studied bodies of the lateral ventricles was associated only with deficits in verbal memory and motor speed. VBRs were unrelated to both positive and negative symptom measures in this sample. Results suggest that more widespread impairment of schizophrenics' cognitive functioning may be related to structural abnormality within the frontal lobes, complementing recent findings linking structural and metabolic abnormalities of this area of the brain to the disease itself.