Grey and white matter proportional relationships in the cerebellar vermis altered in schizophrenia

Magnetic resonance imaging studies frequently report abnormalities of the cerebellar vermis in schizophrenia, though with some discrepancies as to the nature and location of such abnormalities. Imaging studies typically investigate volumetric differences between groups. Yet substantial evidence supports the hypothesis that grey and white matter proportions in the mammalian brain are controlled by scaling relationships. If strong proportional relationships between grey and white matter tissue volumes are observed in the healthy vermis, then disturbances to these proportions might characterize vermian dysmorphology in schizophrenia. Measures of grey and white matter tissue volumes from three anatomical divisions of the vermis were obtained from 52 patients with chronic schizophrenia and 55 healthy controls. Cross-correlations of the tissue class volumes were computed for each subject group, controlling for age. The number of significant correlations in each group were compared. In addition, the grey/white matter ratio was computed within and across each vermian division. Differences in mean and variance were assessed using t and F tests. A false discovery rate of 0.05 controlled for multiple comparisons. Among controls, 11 of 15 correlations were significant. Among patients, eight of 15 correlations were significant. Five of the nine grey/white matter ratios had an increased mean in the patient group, and all of the variances were trend level or significantly increased in the patients. Tissue class volumes in the cerebellar vermis were strongly interrelated in controls. These relationships were disturbed in patients with schizophrenia.