MAPT and Alzheimer disease: A large study focusing on presymptomatic Alzheimer’s disease, for example, found no effect of APOE ɛ4 on subtle cognitive decline, once predictive models were adjusted for Aβ-load.3 In a study on tau PET, effects of APOE ɛ4 on tau were found to be marginal or non-existent once the models were adjusted for Aβ-burden.4