Comparison of regional gray matter volume abnormalities in Alzheimer׳s disease and late life depression with...

Previous voxel-based morphometry (VBM) studies revealed that hippocampal volume loss in patients with late life depression (LLD) is associated with cognitive impairment and a higher risk for dementia. However, LLD patients can experience hippocampal atrophy without cognitive impairment. Thus, while LLD and AD can show comparable hippocampal atrophy, they may encompass different neuropathological changes. Using VBM, we therefore investigated differences in regional gray matter changes in 17 late-onset LLD patients and 21 AD patients (without a history of LLD) who exhibited comparably severe atrophy of the entorhinal cortex and the parahippocampal gyrus on MRI scans for voxel-based specific regional analysis system for AD (VSRAD). Relative to the VSRAD database for healthy individuals, significant atrophy was observed in mesial temporal lobe structures and the anterior cingulate cortex in both groups. Atrophy of the posterior cingulate cortex and precuneus was observed only in the AD group. Comparisons of gray matter volume by multivariate analysis of variance revealed significantly reduced volume of the right middle and inferior temporal gyrus, uncus, posterior cingulate cortex, and precuneus in the AD group only, suggesting impairment of different networks in AD and LLD. Indeed, structural changes in the posterior part of the default-mode network are believed to be associated with cognitive impairments specific to AD.