Carotid Arterial Stiffness Predicts White Matter Lesion Volume in Older Adults

Abstract

Markers of arterial wall stiffness are used commonly as indicators of cardiovascular risk. Stiff conduit vasculature transmits pulse waves with increased velocities, which may lead to end‐organ microvascular damage. However, the association of peripheral vascular stiffness to the brain's vulnerability for vascular impairment has not been established. In the brain, this microvascular damage could include breakdown of the blood‐brain barrier causing leakage of fluid through the cerebrovascular endothelial layer. Fluid‐attenuated inversion recovery (FLAIR) imaging allows the visualization of fluid‐abnormalities in subcortical tissue, which can be quantified as white matter lesions (WML). These WML have been linked to cognitive impairment, and labelled as risk factors for stroke, dementia, and cardiovascular mortality. This research tested the hypothesis that peripheral arterial stiffness predicts levels of WML volume. We examined normotensive controls (CTRL; n = 12; 6 males; age: 42–69 years) as well as normotensive ischemic heart disease patients (IHD; n = 17; 14 males; age: 40–75 years). Common carotid artery diameters were measured during systole and diastole (B‐mode ultrasound images with ECG‐gating), and time‐aligned corresponding blood pressure values were used for measures of arterial strain (strain), arterial stiffness index (β), carotid distensibility, carotid compliance, and arterial elastic modulus. All measures were taken in the supine posture. Magnetic resonance FLAIR imaging at T2 was used to assess periventricular WML volume (WMLv) using SPM software. The IHD and CTRL cohorts had similar WMLv (4.4 ± 3.2 vs. 3.2 ± 3.5 mL; p = 0.33). Also, all participants were normotensive. Therefore, the data were pooled (n = 29) to examine the association between WMLv and peripheral arterial stiffness. Following multiple linear regressions while adjusting for age and BMI, WMLv was correlated with arterial stiffness index (r2 = 0.39, p = 0.001), strain (r2 = 0.37, p = 0.002), carotid distensibility (r2 = 0.36, p = 0.004), carotid compliance (r2 = 0.26, p = 0.009), and absolute change in carotid diameter across one cardiac cycle (r2 = 0.24, p = 0.01). Regardless of the age, BMI, and participant cohort, structural periventricular WMLv correlated with markers of arterial stiffness. These findings support the emerging hypothesis that systemic arterial stiffness affects damage in the microvasculature of the brain. Further, the resulting subcortical structural damage is apparent in older populations regardless of ageing and vascular pathology.Support or Funding InformationSupported by the Canadian Institute of Health Research (201503MOP‐342412‐MOV‐CEEA).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.