Complex interplay of astrogliosis and pathology in preclinical Alzheimer's disease

INTRODUCTION: We evaluated the effects of astrogliosis on Alzheimer's disease (AD) pathology, co-pathology, and symptoms. METHODS: Cross-sectional data from 187 non-demented participants were processed to obtain measures of SMBT-1 standard uptake value ration (SUVR), plasma glial fibrillary acidic protein (GFAP), β-amyloid (Aβ), Centiloids (CL), tau (CenTauR), white matter hyperintensities (WMH), hippocampal volume (HV), and cognition. Linear regressions evaluated pairwise associations, linear regression interaction terms indicated moderating association, and causal mediation analysis evaluated mediating associations. RESULTS: Astrogliosis was associated with CL (p < 0.01), neurodegeneration (0.05 < p < 0.1), and global cognition (p < 0.01). Moderation analyses revealed SMBT-1 SUVR had an attenuating interaction with CL in respect to CenTauR (β = -0.13, p = 0.0006) and memory impairment (β = 0.064, p = 0.05). Plasma GFAP had an attenuating interaction with CL in respect to CenTauR (β = -0.19, p = 0.00001). DISCUSSION: Reactive astrogliosis is an early and important player in the AD development pathway by having an early attenuating effect against Aβ. More work is needed to further understand these complex associations.