Ambulatory pulse pressure brain neuronal fiber integrity andcerebral blood flow in older adults

摘要

Ambulatory blood pressure (ABP) reflects the end-organ vascular stress in dailylife; however, its influence on brain neuronal fiber integrity and cerebralblood flow (CBF) remains unclear. The objective of this study was to determinethe associations among ABP, white matter (WM) neuronal fiber integrity, and CBFin older adults. We tested 144 participants via ABP monitoring and diffusiontensor imaging. The total level and pulsatile indices of CBF were measured byphase-contrast MRI and transcranial Doppler, respectively. Neuropsychologicalassessment was conducted in 72 participants. Among ambulatory and office BPmeasures, elevated 24-h pulse pressure (PP) was associated with the greatestnumber of WM skeleton voxels with decreased fractional anisotropy (FA) andincreased mean diffusivity (MD). Furthermore, these associations remainedsignificant after adjusting for age, antihypertensive use, aortic stiffness, WMlesion volume, and office PP. Radial diffusivity (RD) was elevated in theregions with decreased FA, while axial diffusivity was unaltered. The reductionin diastolic index explained a significant proportion of the individualvariability in FA, MD, and RD. Executive function performance was correlatedwith WM fiber integrity. These findings suggest that elevated ambulatory PP maydeteriorate brain neuronal fiber integrity via reduction in diastolic index.