Localizing Amygdala Structure Differences in Late-Life Depression

Abstract

The amygdala is critical for processing emotional information and plays an important role in late-life depression (LLD). Volumetric studies of the amygdala have been inconclusive with reports of increased, decreased, and no volume changes. This study investigates amygdala shape morphometry to test the hypothesis that if structural changes are specific to certain nuclei, then shape changes may be apparent even when overall volume changes are inconsistent. We have developed a method of shape morphometry based on the work of to localize regions of structural differences. The method relies on generating surface meshes for segmented amygdalae, calculating distances from surface points to the medial manifold, and comparing the distance measures at corresponding surface points between groups. Resulting statistical maps revealed significant structural differences in multiple regions of both amygdalae. Shape morphometry can potentially relate local structure variation to underlying neuroanatomy for a better understanding of LLD neuropathology.