Abstract
Alzheimer's disease (AD) is the most common form of dementia in elderly people. It is an irreversible and progressive brain disease. In this paper, we utilized diffusion-weighted imaging (DWI) to detect abnormal topological organization of white matter (WM) structural networks. We compared the differences between WM connectivity characteristics at global, regional, and local levels in 26 patients with probable AD and 16 normal control (NC) elderly subjects, using connectivity networks constructed with the diffusion tensor imaging (DTI) model and the high angular resolution diffusion imaging (HARDI) model, respectively. At the global level, we found that the WM structural networks of both AD and NC groups had a small-world topology; however, the AD group showed a significant decrease in both global and local efficiency, but an increase in clustering coefficient and the average shortest path length. We further found that the AD patients had significantly decreased nodal efficiency at the regional level, as well as weaker connections in multiple local cortical and subcortical regions, such as precuneus, temporal lobe, hippocampus, and thalamus. The HARDI model was found to be more advantageous than the DTI model, as it was more sensitive to the deficiencies in AD at all of the three levels.
Highlights
Alzheimer’s disease (AD) is the most common form of dementia in elderly people and is characterized by chronic cortical atrophy and neurodegeneration, resulting in behavioral changes, loss of memory and language function, and general cognitive decline [1]
This study involved 26 patients who were diagnosed with probable AD at the Alzheimer’s Disease and Related Disorders Center (ADRDC) in the tertiary hospital of Shanghai Mental Health Center (SMHC) at Shanghai Jiao Tong University School of Medicine. 16 cognitively healthy elderly subjects from the community of Shanghai Chang Ning district were included as the normal control (NC) group
This study investigates the impact of AD on the topological characteristics of the white matter (WM) connectivity network at three hierarchical levels, global, regional, and local level, through tractography data reconstructed using diffusion tensor imaging (DTI) and high angular resolution diffusion imaging (HARDI) methods, respectively
Summary
Alzheimer’s disease (AD) is the most common form of dementia in elderly people and is characterized by chronic cortical atrophy and neurodegeneration, resulting in behavioral changes, loss of memory and language function, and general cognitive decline [1]. It is an irreversible and progressive brain disease and usually diagnosed in people older than 65. Previous studies using T1-weighted structural MRI revealed AD-induced gray matter (GM) atrophy in multiple brain regions, including the hippocampal and entorhinal cortices [4, 5], the temporal and cingulate gyri, the precunei, the insular cortices, the caudate nuclei, the frontal cortices [6], the sensorimotor cortices, the occipital poles, the cerebellum, and the medial thalami [7]
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