Blood Pressure Variability and Plasma Alzheimer's Disease Biomarkers in the SPRINT Trial.

ABSTRACT

Background: Recent observational studies suggest higher blood pressure (BP) variability (BPV) is associated with Alzheimer's disease (AD) biomarkers amyloid-beta (Aß) and tau. Less is known about relationships in interventional cohorts with strictly controlled mean BP levels. Objective: Investigate the longitudinal relationship between BPV and change in plasma AD biomarkers under standard versus intensive BP treatment. Methods: In this post hoc analysis of the SPRINT trial, 457 participants (n = 206 in standard group, n = 251 in intensive group) underwent repeated BP measurement between baseline and 12-months follow-up, and venipuncture at baseline and median (IQR) 3.5 (3.0-4.0) years later to determine plasma AD biomarkers total tau and Aß1-42Aß1-40 ratio. BPV was calculated as tertiles of variability independent of mean. Linear mixed models investigated the effect of BPV×time on AD biomarker levels. Results: Higher BPV was associated with increased levels of total tau in the standard group (ß [95% CI] 1st versus 3rd tertiles of BPV 0.21 [0.02, 0.41], p = 0.035), but not in the intensive group (ß [95% CI] 1st versus 3rd tertiles of BPV -0.02 [-0.19, 0.16], p = 0.843). BPV was not associated with Aß 1-42Aß 1-40 ratio in either group. Mean BP was not associated with biomarkers. Conclusions: Higher BPV was associated with increased plasma total tau under standard BP treatment. Findings add new evidence to prior observational work linking BPV to AD pathophysiology and suggest that, despite strict control of mean BP, BPV remains a risk for pathophysiological change underlying risk for AD.