APOE and Alzheimer disease: They strongly affect Aβ burden in the brain parenchyma1, a core hallmark of AD, but also at the level of the brain vasculature, i.e. cerebral amyloid angiopathy (CAA)1,3, which in turn relates to increased risk for amyloid-related imaging abnormalities (ARIA) in APOE*4 carriers when receiving anti-Aβ antibody treatments4.