Correlations between Gray Matter and White Matter Degeneration in Pure Alzheimer\u2019s Disease, Pure Subcortical Vascular Dementia, and Mixed Dementia

Hyemin Jang,Young Kyoung Jang,Sung Tae Kim,Jong-Min Lee,Hee Jin Kim,Yeshin Kim,Jin-Ju Yang,Duk L Na,Hunki Kwon,Jae Hong Lee,Sang Won Seo,Ko Woon Kim,Jinwoo Hong,Jin San Lee,Kyung Han Lee

doi:10.1038/s41598-017-10074-x

Abstract

Alzheimer’s disease dementia (ADD) and subcortical vascular dementia (SVaD) both show cortical thinning and white matter (WM) microstructural changes. We evaluated different patterns of correlation between gray matter (GM) and WM microstructural changes in pure ADD, pure SVaD, and mixed dementia. We enrolled 40 Pittsburgh compound B (PiB) positive ADD patients without WM hyperintensities (pure ADD), 32 PiB negative SVaD patients (pure SVaD), 23 PiB positive SVaD patients (mixed dementia), and 56 normal controls. WM microstructural integrity was quantified using fractional anisotropy (FA), axial diffusivity (DA), and radial diffusivity (DR) values. We used sparse canonical correlation analysis to show correlated regions of cortical thinning and WM microstructural changes. In pure ADD patients, lower FA in the frontoparietal area correlated with cortical thinning in the left inferior parietal lobule and bilateral paracentral lobules. In pure SVaD patients, lower FA and higher DR across extensive WM regions correlated with cortical thinning in bilateral fronto-temporo-parietal regions. In mixed dementia patients, DR and DA changes across extensive WM regions correlated with cortical thinning in the bilateral fronto-temporo-parietal regions. Our findings showed that the relationships between GM and WM degeneration are distinct in pure ADD, pure SVaD, and mixed dementia, suggesting that different pathomechanisms underlie their correlations.

Highlights

Alzheimer’s disease dementia (ADD) and subcortical vascular dementia (SVaD) are the two representative causes of dementia
To evaluate correlation between gray matter (GM) and white matter (WM) degeneration, we first investigated the patterns of WM microstructural changes and GM degeneration in patients with pure ADD, pure SVaD, and mixed dementia, which were determined by Pittsburgh compound B (PiB) PET result and WM hyperintensities degree as described in the Methods
We report a novel finding regarding correlation between WM microstructural changes and cortical thinning in pure ADD, pure SVaD, and mixed dementia

Summary

Introduction

Alzheimer’s disease dementia (ADD) and subcortical vascular dementia (SVaD) are the two representative causes of dementia. To evaluate correlation between GM and WM degeneration, we first investigated the patterns of WM microstructural changes (using DTI) and GM degeneration (using cortical thickness analysis) in patients with pure ADD, pure SVaD, and mixed dementia, which were determined by Pittsburgh compound B (PiB) PET result and WM hyperintensities degree as described in the Methods. We hypothesized that mixed dementia would show both ADD and SVaD characteristic and that an increase in DR and a decrease in DA would correlate to cortical thinning.

Results

Conclusion