Abstract
Background and Objectives. White matter hyperintensities (WMH) correlate with Alzheimer disease (AD) biomarkers cross-sectionally and modulate AD pathogenesis. Longitudinal changes have been reported for AD biomarkers, including concentrations of cerebrospinal fluid (CSF) Aβ42, Aβ40, total tau (Tau) and phosphorylated tau181 (pTau181), standardized uptake value ratio (SUVR) from the molecular imaging of cerebral fibrillar β-amyloid with positron emission tomography (PET) using [11C] Pittsburgh Compound-B (PiB), magnetic resonance imaging (MRI)-based hippocampal volume and cortical thickness. Correlations between established AD biomarkers and the longitudinal change for WMH have not been fully evaluated, especially among cognitively normal individuals across the adult lifespan.
Methods. We jointly analyzed the longitudinal data of WMH volume and each of the established AD biomarkers and cognition from 371 cognitively normal individuals whose baseline age spanned from 19.6 to 88.20 years from four longitudinal studies of aging and AD. A two-stage algorithm was applied to identify the inflection-point of baseline age whereby older participants had an accelerated longitudinal change in WMH volume, in comparison to the younger participants. The longitudinal correlations between WMH volume and AD biomarkers were estimated from the bivariate linear mixed effects models.
Results. A longitudinal increase in WMH volume was associated with a longitudinal increase in PET amyloid uptake, and a decrease in MRI hippocampal volume, cortical thickness, and cognition. The inflection-point of baseline age in WMH volume was identified at 60.46 (95% CI: 56.43∼64.49) years, with the annual increase for the older participants (83.12 [SE=10.19] mm3/year) more than 13 times faster (p<0.0001) than that for the younger participants (6.35 [SE=5.63] mm3/year). Accelerated rates of change among the older participants were similarly observed in almost all the AD biomarkers. Longitudinal correlations of WMH volume with MRI, PET amyloid biomarkers, and cognition appeared to be numerically stronger for the younger participants, but not significantly different from those for the older participants. Carrying APOE ε4 alleles did not alter the longitudinal correlations between WMH and AD biomarkers.
Discussion. Longitudinal increases in WMH volume started to accelerate around a baseline age of 60.46 years, and correlated with the longitudinal change in PET amyloid uptake, MRI structural outcomes, and cognition.
- Received July 7, 2022.
- Accepted in final form March 20, 2023.
- © 2023 American Academy of Neurology
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