White Matter Predictors of Cognitive Functioning in Older Adults

Abstract

Background Few studies have applied multiple imaging modalities to examine cognitive correlates of white matter. We examined the utility of T2-weighted MRI-derived white matter hyperintensities (WMH) and diffusion tensor imaging-derived fractional anisotropy (FA) to predict cognitive functioning among older adults. Methods Quantitative MRI and neuropsychological evaluations were performed in 112 older participants from an ongoing study of the genetics of Alzheimer’s disease (AD) in African Americans. Regional WMH volumes and FA were measured in multiple regions of interest. We examined the association of regional WMH and an FA summary score with cognitive test performance. Differences in WMH and FA were compared across diagnostic groups (i.e., normal controls, mild cognitive impairment, and probable AD). Results Increased WMH volume in frontal lobes was associated with poorer delayed memory performance. FA did not emerge as a significant predictor of cognition. White matter hyperintensity volume in the frontal and parietal lobes was increased in MCI participants and more so in AD patients relative to controls. Discussion These results highlight the importance of regionally-distributed small vessel cerebrovascular disease in memory performance and AD among African American older adults. White matter microstructural changes, quantified with DTI, appear to play a lesser role in our sample.

Imaging and neuropsychological correlates of white matter lesions in different subtypes of Mild Cognitive Impairment: A systematic review

“…Conversely, another theory follows the retrogenesis model and proposes that white matter change is independent of the gray matter pathology. The white matter will follow the reverse order of myelinogenesis, in which white matter will degenerate first in the late-myelinating WM tracts, such as the inferior and super longitudinal fasciculus and the uncinate fasciculus (Meier et al, 2012). In short, our current results suggest that WML detected in T2 or FLARE images of MCI cannot differentiate different subtypes of MCI and is yet to be a reliable prognostic marker in determining the risk of dementia.…”

“…First, WML is associated with reduced cognitive functioning in MCI. It is widely accepted that a severe grade of WML has a detrimental impact on cognitive functioning including executive function, attention, processing speed, and global cognition (Jokinen, Lipsanen, & Schmidt, 2012;Meier et al, 2012;Pantoni, Poggesi, & Inzitari, 2007;Prins & Scheltens, 2015;Xiong & Mok, 2011). Second, the location or the spatial distribution of the WML has a differential impact on cognitive functioning.…”

Loss of Nicastrin from Oligodendrocytes Results in Hypomyelination and Schizophrenia with Compulsive Behavior

“…White matter abnormalities and changes in myelin genes have been linked to multiple psychiatric disorders (including schizophrenia and obsessive-compulsive behavior (9, 36)), as well as in Alzheimer disease (37). Meanwhile, recently identified models of compulsive grooming and trichotillomania similar to that displayed by our conditional knock-out mice involve genes important for neural (i.e.…”

Age exacerbates HIV-associated white matter abnormalities

“…Fractional anisotropy (FA) is a commonly reported scalar metric derived from the diffusion tensor that provides a measure of the directionality of water diffusion. Research has shown that while FA and WMH are related, they likely reflect distinct structural manifestations of white matter (Vernooij et al 2009; Meier et al 2012; Maillard et al 2013; Aine et al 2014), and thus may both be valuable for assessing the extent of white matter disturbances associated with HIV.…”