Abstract P366: High Burden of Tract-Specific White Matter Hyperintensities Relates to Impaired Microstructural Integrity of Distal White Matter Tracts in Community-Dwelling Elders

Abstract

Background and purpose: White matter hyperintensities (WMH) are common in elderly individuals and contribute to age-related cognitive dysfunction. Converging evidence indicates that WMH affect white matter (WM) microstructural integrity in WMH and their penumbra. We aimed to investigate whether this effect extends to the distal WM tracts, and to examine the association between distal WM microstructural integrity and cognitive dysfunction in community-dwelling elderly people. Methods: Brain MRI data including FLAIR and DTI sequences of 174 participants (74 ± 5 years) of the Shanghai Aging Study (SAS) were collected and analyzed. For each participant, WMH lesions were segmented automatically. Eighteen major WM tracts were reconstructed using automated quantitative tractography, and the mean diffusivity (MD) of distal WM tracts (excluding an area of 12 mm around the WMH) was calculated. Multivariable linear regression was performed. Results: A high burden of tract-specific WMH was related to a high MD of distal WM tracts in the forceps major (FMA), anterior thalamic radiations (ATR), cingulum cingulate gyrus (CCG), corticospinal tract (CST), superior longitudinal fasciculus-parietal (SLFP), superior longitudinal fasciculus-temporal (SLFT), and uncinate fasciculus (UNC). Furthermore, a high MD of distal tracts was linked to worse attention and executive function in the forceps minor (FMI), right CCG, left inferior longitudinal fasciculus (ILF), SLFP, SLFT and UNC. Conclusions: The effect of WMH on the microstructural integrity of WM tracts may propagate along tracts to distal regions farther than the penumbra and eventually might affect attention and executive function.