Grinberg, Lea

Abstract INTRODUCTION We integrate visual and quantitative metrics in white matter and medial temporal lobe to examine relationships with neuropathology in a community cohort. METHODS Postmortem in situ MRI (T1, T2, DWI) was performed in 25 human brains, followed by visual ratings (Fazekas, MTA, ERICA, Koedam). Neuropathology included ADNC, LATE-NC, hippocampal sclerosis, PART, ARTAG, Lewy pathology, and CAA. RESULTS Increased Fazekas score was linked to aging, lower education, hypertension, higher basilar artery wall thickness, and greater Braak NFT stage. WMH volume also correlated with lacunes, Thal phase, and CERAD score that was not observed using Fazekas. Hippocampal volumes were lower in elderly, less educated people and were associated with higher atrophy scores and higher Braak NFT stage. Higher amygdala volume was only associated with higher CERAD score. DISCUSSION Quantitative MRI may detect neuropathologic associations more sensitively than visual ratings. Tau pathology is a key predictor of WMH burden and hippocampal atrophy.

Abstract The standard approach to quantify amyloid (Aβ) PET averages uptake within a single cortical mask that assumes no clinically relevant spatial heterogeneity in uptake patterns. Here, in a sample of 12,379 clinically impaired participants taken from four phenotypically diverse cohorts we use data-driven approaches to discover heterogeneous patterns of Aβ-PET binding, uncovering a reproducible and clinically relevant pattern of posterior predominant Aβ-PET binding. In particular, Aβ-PET positive participants who have posterior predominant binding are less likely to be APOE -ε4 carriers, more severely impaired, have thinner cortex in posterior regions, and greater posterior tau PET burden. Furthermore, in a subsample of participants with neuropathological assessment, participants with posterior predominant Aβ binding have a higher likelihood of having cerebral amyloid angiopathy at autopsy. These findings suggest that Aβ-PET accumulates along two orthogonal axes with biological and clinical relevance, indicating that the standard approach to assess Aβ-PET is insufficient to capture meaningful signal from Aβ-PET imaging. This work has implications for the diagnosis and treatment of Alzheimer’s disease and extends our understanding of the mechanisms governing variable Aβ-PET distribution and its downstream effects.