Analysis of structural connectivity on progression of Alzheimer's disease using diffusion tensor imaging

The occurrence of Alzheimer's disease (AD) in the elderly individuals has been increasing at an alarming rate throughout the world over the past decade. Diffusion Tensor Imaging (DTI) has been widely used to study the white matter tracts in the human brain and for the estimation of structural connectivity parameters through the progression of the disease. Previous studies using fMRI focus on functional decline and adding on to this, DTI helps in analyzing the topological and structural integrity. Histopathological studies of the disease have revealed that major cortical neuronal loss occurred in Corpus Callosum and Cingulate Gyrus regions of the brain. In this work, DTI images of four AD patients for three progressive years have been obtained and the structural connectivity parameters namely: Fractional Anisotropy (FA), Axial Diffusivity, Radial Diffusivity and Mean Diffusivity have been estimated at the onset of the disease and for the three progressive years. Results show that the FA values decreased in the progressive years for all patients whereas the diffusivity parameters increased every year showing abnormalities in the connectivity parameters.

I. Introduction

Dementia refers to the group of diseases which affect the human brain cells leading to sustained and inexorable loss of memory and cognition. Alzheimer's disease has known to be the most common type of dementia, being classified into stages namely: Mild, Moderate and Severe. AD has been reported to advance in the progressive years and affect the thinking ability of patients which eventually leads to complete memory loss and loss of bodily functions [1], [2], [16]. The disease, with no curative found till date has been chronic in nature and its end result has been lethal.