Microvascular physiology differs in older adults with varying vascular risk and white matter lesion burden

Motivation: While links between microvascular physiology and white matter lesion burden have largely been studied in older adults with high vascular risk, some individuals exhibit high lesion burden despite presenting with low vascular risk. Goal(s): To determine whether associations between hemo-metabolic physiology and lesion burden vary in older adults according to vascular risk. Approach: We compared MRI-based measures of oxygen supply and oxygen extraction fraction (OEF) between older adults categorized by vascular risk and white matter lesion burden. Results: In low-risk individuals, OEF was uniquely lower in the subgroup with higher lesion burden, while oxygen supply did not differ between the subgroups. Impact: Impaired oxygen extraction may represent an important and independent contributor to white matter lesion burden in older adults in whom lesion burden is high despite the absence of conventional vascular risk factors.