Abstract
Degeneration of cerebral white matter is commonly observed in aging, and the associated degradation in neural connectivity contributes to cognitive decline in older adults. Vascular dysfunction has been implicated as a potential mechanism for general age-related neural tissue deterioration; however, no prior study has examined the direct relationship between cortical vascular health and subcortical white-matter integrity. In this work, we aimed to determine whether blood supply to the brain is associated with microstructural integrity of connective tissue, and whether such associations are regionally specific and mainly accounted for by aging. We examined the association between cerebral blood flow (CBF) in the cortical mantle, measured using arterial spin labeling (ASL), and subcortical white-matter integrity, measured using diffusion tensor imaging (DTI), in a group of healthy adults spanning early to late adulthood. We found cortical CBF to be significantly associated with white-matter integrity throughout the brain. In addition, these associations were only partially tied to aging, as they remained even when statistically controlling for age, and when restricting the analyses to a young subset of the sample. Furthermore, vascular risk was not a prominent determinant of these effects. These findings suggest that the overall blood supply to the brain is an important indicator of white-matter health in the normal range of variations amongst adults, and that the decline in CBF with advancing age may potentially exacerbate deterioration of the connective anatomy of the brain.
Highlights
Degeneration of the cerebral white matter is widely observed in aging, and has been associated with cognitive dysfunction [1,2,3,4,5,6,7,8]
To date, there remains a gap of knowledge on the extent to which cortical blood supply is associated with tissue integrity in non-lesioned, normal-appearing white matter in the healthycontrol population, or on whether such associations exist in the absence of vascular risk factors
Age Reductions in fractional anisotropy (FA) were observed with advancing age, with statistically significant effects found in the corpus callosum, corona radiata, cingulum, superior longitudinal fasciculus, internal capsule and uncinate fasciculus (Figure 1A, shown in blue)
Summary
Degeneration of the cerebral white matter is widely observed in aging, and has been associated with cognitive dysfunction [1,2,3,4,5,6,7,8]. To date, there remains a gap of knowledge on the extent to which cortical blood supply is associated with tissue integrity in non-lesioned, normal-appearing white matter in the healthycontrol population, or on whether such associations exist in the absence of vascular risk factors. DTI-based observations of white-matter microstructural changes have consistently been associated with non-demented aging [24,25,29,30,31,32,33,34,35,36] and neurological diseases such as Alzheimer’s disease [14,32,37,38,39,40,41], cerebral small vessel disease [21] and amyloid angiopathy [42]
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