The impact of age and vascular risk factors on white matter microstructural organization

Authors

• OA Williams
• Y An
• L Beason-Held
• Y Huo
• BA Landman
• SM Resnick

Abstract

White matter microstructure can be measured with diffusion tensor imaging (DTI). While increasing age is a predictor of white matter microstructure, it is also important to clarify the effects of other possible modifiers such as vascular risk factors. We investigated 682 cognitively normal participants from the Baltimore Longitudinal Study of Aging (age 50-95, 56.5% female) with a total of 1476 DTI scans. White matter microstructure was measured using fractional anisotropy (FA) and mean diffusivity (MD). A vascular burden score was calculated as a cumulative score for five risk factors (hypertension, obesity, elevated cholesterol, diabetes and smoking). Linear mixed effects models assessed the impact of baseline vascular burden score on FA and MD at baseline and on rates of change over a mean follow-up of 3.7 years. At baseline, higher vascular burden was associated with lower FA and higher MD in a range of WM structures including association, commissural, and projection fibers. Higher baseline vascular burden was also associated with greater decline in FA in the hippocampal part of the cingulum and the fornix (crus)/stria terminalis, and with greater increases in MD in the splenium of the corpus callosum. Our findings show that modifiable vascular risk factors (1) have a negative impact on white matter microstructure and (2) are associated with faster microstructural deterioration of temporal white matter regions and the splenium of the corpus callosum in cognitively normal adults. Reducing vascular burden could modify the rate of deterioration in white matter and could decrease age-related cognitive decline and impairment.

Scientific Focus Area: Neuroscience

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