Association of Arterial Stiffness and Changes in Brain Structure and Function in the UK Biobank

Abstract

While evidence suggests there is indeed a relationship between arterial stiffness and changes in brain structure and function cross-sectionally, the longitudinal relationship between arterial stiffness and changes in brain structure and function is unclear. Also unclear is whether a regional effect of arterial stiffness on brain structure exists, or if the effect is homogenous across brain regions. Using a healthy cohort of the UK Biobank study (N = 1858, meanSD: 61  7 years), we investigated the longitudinal association between changes in arterial stiffness index (ASI) and brain structure (grey matter cortical thickness, whole brain grey matter volume, white matter hyperintensity volume) and function (cognitive performance in 6 tests) over 2.5  1 years. We also examined the association between baseline ASI and all structural and functional brain outcomes 8-11 years post-baseline (N = 630). Prior to post-hoc correction, we observed a significant effect of changes in ASI over 2.5  1 years on grey matter cortical thickness in 11 brain regions contributing to reductions between 0.0004-0.0024mm annually, but none of the 11 regions remained significant post-correction. Following correction there was also no effect of changes in ASI on whole brain grey matter volume (p = 0.76), white matter hyperintensity volume (p = 0.84), or cognitive performance in the domains of interest. Baseline ASI was not associated with regional grey matter cortical thickness, white matter hyperintensity volume, or cognitive function, but did have a significant negative association with whole brain grey matter volume 8.5  1.05 (p = 0.015) years later and 11  1.02 (p = 0.03) years later. Our findings suggest that taken with the effect of age, elevations in ASI may have an additive effect to accelerate changes in brain structure beyond the range that is to be expected as a part of normal aging. Our findings also suggest the relationship between ASI and reductions in whole brain grey matter volume may require long-term exposure to elevations in arterial stiffness in otherwise healthy older adults.