MAPT and Alzheimer disease: Gordon and colleagues, for example, revealed that when both Aβ and tau PET values were combined in a model, increased tau uptake, but not Aβ, was associated with changes in cortical thickness.31 These findings corroborate the well-established spatiotemporal model of amyloid accumulation, in which Aβ levels are anticipated to have plateaued prior to symptom onset and macroscale neurodegeneration.36 Indeed, grey matter atrophy manifesting as cortical thinning is often considered a late event in the neurodegenerative cascade of AD.