Diffusion tensor imaging (tractography) in elderly people with mixed dementia and mild Alzheimer's disease

Abstract

AbstractBackgroundCerebral tractography is a Magnetic Resonance Imaging technique that allows you to visualize the white matter fascicles that connect different parts of the brain. It is based on the diffusion of water in biological tissues, through which fiber tracts are evaluated in a three‐dimensional space, which allows to obtain the Anisotropy Fraction (FA) and Medium Diffusivity (DM). Tractography allows correlating the integrity of these pathways with cognitive function. The objective of our study was to identify anatomical regions with alterations in AF in mixed dementia compared to AD.Method16 patients were included; 8 with Mixed Dementia (DMix) and 8 with Alzheimer's Disease (AD). Mean, standard deviations and frequencies were used, as well as Chi‐square and Mann‐Whitney tests. A linear regression model was used to determine the association between Tractography and performance in cognitive domains, adjusted for age and educational level.ResultsThe mean age of the participants was 85 ± 7.9 years (p ≤.57), 69% were women (p ≤.10) and the educational level was 11 ± 6.0 years (p ≤.87). Participants with AD had a worse cognitive performance (NEUROPSI: 68.5 ± 11.6 points, p ≤.02) compared to the DMix group. When analyzing by cognitive domains, patients in the DMix group had a worse performance in phonological verbal fluency (7.0 ± 3.5 words, p ≤.05). Regarding neuroimaging, significant differences were observed in participants with DMix in the Anisotropy Fraction (AF) in the following tracts: right cerebral peduncle (0.5557 ± 0.0121, p ≤.05), left cerebral peduncle (0.5476 ± 0.0121, p ≤0.01), right external capsule (0.3346 ± 0.0163, p ≤0.01) and left cingulate gyrus (0.3756 ± 0.0241, p ≤0.05) and mean diffusivity in the right thalamic posterior radiation (0.0010 ± 0.0000, p ≤ 0.03) and left external capsule (0.0012 ± 0.0001, p ≤0.03).ConclusionTractography allows quantifying and differentiating anatomical regions with myelin damage in mixed dementia compared to AD.