Blood pressure dynamic instability and neurodegeneration in older adults

BackgroundBlood pressure variability (BPV) is an age-related hemodynamic risk factor for neurodegeneration, but it remains unclear whether distinct forms of BPV display independent or interactive effects on brain health.ObjectiveInvestigate whether high beat-to-beat BPV, when combined with increased pulse pressure variability, a form of BPV associated with arterial stiffness, exacerbates markers of neurodegeneration.MethodsOlder adults (N = 105) without major neurological or systemic disease were recruited for brain magnetic resonance imaging and continuous blood pressure (BP) monitoring to quantify beat-to-beat BPV through systolic average real variability (ARV) and pulse pressure variability using arterial stiffness index (ASI). The interactive effect of ARV and ASI on medial temporal lobe atrophy, plasma neurofilament light chain (NfL), and plasma glial fibrillary acidic protein (GFAP) was studied using hierarchical linear regression in older adults. Voxel-based morphometry was used to confirm region-of-interest analysis findings.ResultsThe interaction between higher ARV and higher ASI was significantly associated with left-sided medial temporal lobe atrophy in both the region-of-interest (left hippocampus β = -252.79, p = 0.0002, right hippocampus β = -193.56, p = 0.001, left entorhinal cortex β = -0.13, p = 0.007), and false discovery rate-corrected voxel-based morphometry analysis (p = 0.03). The interactive effect was also significantly associated with increased plasma NfL (β = 3.88, p = 0.01), but not GFAP.ConclusionsThe interaction between ARV and ASI is independently associated with neurodegenerative markers, including medial temporal lobe atrophy and plasma NfL, in older adults. These findings suggest that greater hemodynamic instability is associated with increased risk for neurodegenerative processes.