The association of blood pressure variability with white matter integrity and cognitive impairment in cerebral amyloid angiopathy

Abstract

AbstractBackgroundEmerging evidence suggests that blood pressure variability (BPV) may contribute to small vessel disease (SVD) progression and cognitive impairment beyond the deleterious effects of elevated blood pressure, but the mechanisms remain largely unknown. This study investigates if BPV is associated with white matter (WM) microstructural integrity and the slope of cognitive decline in elderly individuals with cerebral amyloid angiopathy (CAA), a well characterized type of SVD.MethodWe recruited 94 non‐demented individuals (73.3 ± 7.0 y, 40 F, MMSE 27.7 ± 1.5) from a memory‐clinic cohort with and without possible/probable CAA with available neuropsychological evaluation and 3.0 T research MRI. Visit‐to‐visit BPV was assessed using the coefficient of variation derived from the serial outpatient BP measures during a 5‐year interval. A novel diffusion tensor imaging marker – peak width of skeletonized mean diffusivity (PSMD) – was used to evaluate the WM integrity. Using linear regression models, we evaluated the association of PSMD with BPV, adjusted for standard cardiovascular risk factors.ResultWe found a significant association between loss of WM integrity and high systolic BPV (β = 0.37, P < 0.001), but not mean BP. The association remained significant after adjusting for age, antihypertensive medication usage, diabetes, smoking, and body mass index. Furthermore, the association of BPV with WM integrity was stronger when CAA was present (P for interaction = 0.018). Higher BPV at baseline was associated with worse executive function in CAA patients at 2‐year follow‐up (β = ‐0.53, P = 0.003), adjusted for baseline function.ConclusionOur findings show that visit‐to‐visit BP fluctuations are associated with loss of WM microstructural integrity and cognitive decline. The association between BP variability and WM integrity might in part be driven by CAA pathology. Further studies are warranted to disentangle the relationship between BP fluctuations, microvascular injury, and cognitive impairment in older adults.