A morphological study of the shape of the corpus callosum in normal, schizophrenic and bipolar patients

Abstract

Abnormalities in the morphology of the corpus callosum (CC) have previously been found to be involved in the cognitive impairments or abnormal behaviour seen in patients with mental disorders such as schizophrenia and bipolar disorder. The present study investigated morphological shape differences of the CC in a large cohort of 223 participants between normal, schizophrenic, and bipolar patients on midsagittal sections of MRI scans (n=111), and CT scans (n=62) and cadaver (n=50) samples. Healthy population samples were compared to a mental disorder population sample in order to determine potential morphological shape variations associated with schizophrenia and bipolar disorder to aid in the disorder diagnostic process. Landmark-based methodology was used to contour the CC shape by plotting 29 landmarks that served as standard positions to allow for radial partitioning and thickness partitioning to be performed in order to determine shape variations within the specific localized anatomical sections of the CC. Shape analysis was performed using Ordinary Procrustes averaging and superimposing the landmarks of samples to define an average landmark position for the specific regions of the CC. The results showed no significant global or region-specific sex or age-related CC shape differences across the entire study sample as well as within sample groups. No significant shape differences were found between the different mental disorders. Although not significant, schizophrenia and bipolar CC shapes differed mostly in the genu-rostrum, posterior body, isthmus, and splenium. Sample group comparisons yielded significant differences between all sample groups for all global CC measurement parameters and in various CC sub-regions. The findings of the present study, suggest that the CC in schizophrenia and bipolar differs significantly compared to healthy controls, specifically in the anterior body and isthmus for schizophrenia and only in the isthmus for bipolar disorder.