Sex difference in white matter degeneration in MCI adults: Multi‐modal MRI analysis

• Published in: Alzheimer's & dementia Vol. 16
• Main Author: Kim, Jeongchul
• Format: Journal Article
• Language: English
• Published: 01.12.2020
• ISSN: 1552-5260; 1552-5279
• DOI: 10.1002/alz.044828

Background Although the development and progression of Alzheimer's disease (AD) are characterized by significant sex differences, the factors underlying sex differences in AD are not well understood. This study explored sex differences in white matter (WM) degeneration patterns among mild cognitive impairment (MCI) adults in an exercise intervention study. Method Longitudinal MR images for 32 adults with MCI were acquired as part of a randomized controlled trial investigating an exercise intervention (n=15 aerobic exercise, n=17 stretching control). Brain MRI was acquired at baseline and 6 months later after the exercise intervention on a 3T scanner using a 32‐channel head/neck coil. High‐resolution structural anatomic T1‐weighted and diffusion tensor images of each subject were collected, from which the longitudinal changes of diffusion metrics (FA, MD and Fiber Volume Fraction [FV]) and volume changes (Jacobian Determinant, JD) rate were estimated for 48 WM regions of interest (ROIs) defined by the JHU‐WM Atlas. The total WM degeneration for each individual was defined by counting the number of ROIs demonstrating > 5% changes in diffusion metrics or JD compared to the baseline considering fiber crossing environments (Figs. 1 and 2). Result No statistically significant change was observed in FA, MD, FV, JD and WM degeneration for both groups during the 6‐month period. But, increase in FA was observed in Right Posterior Corona Radiata for the whole study population (p=0.0087). A wide distribution of WM degeneration was observed over the different brain regions with a higher probability of WM degeneration in Left Posterior Limb of Internal Capsule (59%), Right Retrolenticular Part of Internal Capsule (56%) and Left Anterior Corona Radiata (56%). Higher WM degeneration was observed in women compared to men (p=0.029) after adjustment for age, exercise intervention and APOE4 status. Conclusion Group‐level changes or differences were not observed for most longitudinal MRI measures due to the heterogeneity of WM degeneration in MCI adults. However, a multi‐modal MRI approach integrating morphometric information with diffusion properties could elucidate the sex differences in WM degeneration among MCI adults.