Changes Over Time of Diffusion MRI in the White Matter of Aging Brain, a Good Predictor of Verbal Recall

Abstract

Objective: Extensive research using water-diffusion MRI reported age-related modifications of cerebral White Matter (WM). Moreover, water-diffusion parameter modifications have been frequently associated with cognitive performances in the elderly sample, reinforcing the idea of aging inducing microstructural disconnection of the brain which in turn impacts cognition. However, only few studies really assessed overtime modifications of these parameters and their relationship with episodic memory outcome of elderly. Materials and Methods: One-hundred and thirty elderly subjects without dementia (74.1 ± 4.1 years; 47% female) were included in this study. Diffusion tensor imaging (DTI) was performed at two-time points (3.49 ± 0.68 years apart), allowing the assessment of changes in water-diffusion parameters over time using a specific longitudinal pipeline. White matter hyperintensity (WMH) burden and gray matter (GM) atrophy were also measured on FLAIR and T1-weighted sequences collected during these two MRI sessions. Free and cued verbal recall scores assessed at the last follow-up of the cohort were used as episodic memory outcome. Changes in water-diffusion parameters over time were included in serial linear regression models to predict retrieval or storage ability of elderly. Results: GM atrophy and an increase in mean diffusivity (MD) and WMH load between the two-time points were observed. The increase in MD was significantly correlated with WMH load and the different memory scores. In models accounting for the baseline cognitive score, GM atrophy, or WMH load, MD changes still significantly predict free verbal recall, and not total verbal recall, suggesting the specific association with the retrieval deficit in healthy aging. Conclusion: In elderly, microstructural WM changes are good predictors of lower free verbal recall performances. Moreover, this contribution is not only driven by WMH load

White matter microstructure associations with episodic memory in adults with Down syndrome: a tract-based spatial statistics study

“…Moreover, WM integrity has been found to be associated with cognitive decline and, more specifically, impaired episodic memory in non-demented adults from non-DS populations [12,15,24]. For example, Nicholas et al (2020) found that increases in frontal MD across time were associated with decreases in the ability to correctly recall words (i.e., free recall) in older adults without AD [25]. Remy et al (2015) found an association between lower FA in the medial temporal lobe and worse episodic memory in older adults without AD [26].…”

Aging and white matter microstructure and macrostructure: a longitudinal multi-site diffusion MRI study of 1,184 participants

“…Consequently, this leads to a decrease in fractional anisotropy. This has traditionally been attributed to myelin loss and/or decreased axonal volume fractions and densities (17, 21, 37, 38), with supplemental evidence provided through advanced multicompartment modeling (18, 21). However, care must be taken when interpreting these indices as highly specific markers of tissue microstructure, as diffusion (and DTI in particular) is sensitive to a number of potential biophysical changes (39).…”

Digital sleep measures and white matter health in the Framingham Heart Study

“…The key outcomes of our analysis were the demonstration that: (1) stable sleep was associated with better WM health (increased FA and reduced MD); (2) actigraphic periods of wake during the sleep period were associated with increased MD; (3) one marker of sleep fragmentation which covaries with respiratory chemoreflex activation was associated with reduced FA and increased MD, DTI markers of deteriorated WM integrity [33][34][35]; (4) both oxygen desaturation index and oxygen saturation time under 90% were associated with pathological directions of DTI signals. These results were obtained in a community dwelling cohort, rather than a sleep clinic population, and have implications for brain health at the population level [21,[36][37][38][39].…”