APOE and Alzheimer disease: We hypothesize that the APOE effect will be specific to the AD cascade [15], such that when compared to biomarker negative participants, we will observe higher frequencies of the APOE ε4 allele and lower frequencies of the ε2 allele among the amyloid positive participants and among the biomarker (both amyloid and neurodegeneration) positive participants but not among the SNAP participants.