Association between basal forebrain tau and memory in older adults without dementia

Abstract

AbstractBackgroundTau pathology is a hallmark of Alzheimer’s disease and can be assessed in vivo using 18F‐Flortaucipir positron emission tomography (PET). Recent literature suggests a role of the basal forebrain (BF) early in tau accumulation pathways, but knowledge on BF tau and cognition is limited. We assessed the utility of BF flortaucipir PET signal and its relationship with cognition in a sample of individuals without dementia.Method114 older adults in the Baltimore Longitudinal Study of Aging underwent flortaucipir PET imaging. Standardized uptake value ratio (SUVR) was computed in regions of interest (ROI’‐s) (BF, entorhinal cortex (EC), hippocampus (HC)) and in a control region with no tau pathology (4th ventricle, including choroid plexus). 110 participants had concurrent and prospective cognitive testing (memory). The relationship between BF SUVR and cognition was assessed with correlation and linear mixed effects models.Result4th ventricle SUVR was positively associated with SUVR of the EC (Pearson’s r=.33, p<.001) and HC (r=.55, p<.001), but not the BF (r=.16, p=.10). In unadjusted analyses, higher BF SUVR was associated with amyloid positivity (difference in means=.12, p=.01) and lower memory (r=‐.21, p=.03) at baseline. There was no association between baseline BF SUVR and concurrent or prospective change in cognition once adjusted for age, sex, and education.ConclusionThe lack of a relationship between BF and 4th ventricle SUVR may indicate lower susceptibility of BF to non‐specific binding signal spillover compared to the EC and HC. BF SUVR was associated with amyloid positivity and memory in the expected directions, but the association with memory was not statistically significant after controlling for factors relevant to cognition. Further analysis is necessary to assess whether the lack of an association with cognition is due to limited statistical power.