APOE and Alzheimer disease: Participants differed by their amyloid status on baseline neuropsychological testing visit age, family history of AD, APOE ε4 allele carriage, and the age at most recent amyloid PET scan (P < 0.01), such that A+ participants tended to be older, carried at least one APOE ε4 allele, and were positive for family history of AD.