Statistical Examination of Myelinated Cortical Thickness in Bipolar Disorder

Abstract

The human cerebral cortex, the outermost layer of the brain, is typically considered in imaging studies to consist of grey matter (GM), with white matter (WM) lying below it. With better imaging techniques, a third tissue type, found between GM and WM, can be identified. This layer contains myelinated axons and is found in the cortex, thus we call it intracortical myelin (ICM), or myelinated grey matter (GMm). We examined the cortical thickness measurements in female patients with bipolar I or II disorders (BD) versus healthy controls. Previous studies have only examined the thickness of the entire cortex, the GM. We developed a processing pipeline and a statistical tool for examining the ICM thickness between two groups. Results show that there are potential differences in GMm between BD and control groups. Further regional and statistical analysis is required to identify the regions of greatest difference, and to confirm significant differences between BD and control groups.