Computed tomography (CT) studies have demonstrated that lateral ventricular size measured by ventricular brain ratio (VBR), as well as third ventricle width, is statistically enlarged in schizophrenics. Moreover, these cerebral abnormalities differ according to symptomatology evaluated with a positive and negative symptom scale. The aim of this study was to investigate, using CT scans, healthy siblings of schizophrenics, and relate the results to their ill siblings. Nineteen healthy siblings of 12 previously studied schizophrenics underwent CT scans, which were compared to those of their related schizophrenic sibling and to 17 unrelated control subjects. The results showed that in ten of 12 families, schizophrenics have larger ventricles (lateral and third ventricles) than their healthy siblings. Ventricular enlargement of healthy siblings was correlated with severity of negative symptoms of their ill sibling. Implications of a familial contribution for ventricular size and negative symptoms are discussed.
