Characterisation of Posterior Predominant Amyloid PET Binding Across Multiple Cohorts
The standard approach to quantify amyloid (A{beta}) 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 A{beta}-PET binding, uncovering a reproducible and clinically relevant pattern of posterior predominant A{beta}-PET binding. In particular, A{beta}-PET positive participants who have posterior predominant binding are less likely to be APOE-{varepsilon}4 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 A{beta} binding have a higher likelihood of having cerebral amyloid angiopathy at autopsy. These findings suggest that A{beta}-PET accumulates along two orthogonal axes with biological and clinical relevance, indicating that the standard approach to assess A{beta}-PET is insufficient to capture meaningful signal from A{beta}-PET imaging. This work has implications for the diagnosis and treatment of Alzheimers disease and extends our understanding of the mechanisms governing variable A{beta}-PET distribution and its downstream effects.