APOE and Alzheimer disease: Notably, the Baltimore Longitudinal Study of Aging detected interactions of APOE ε4 allele with openness and agreeableness on the risk of Alzheimer’s disease, in which high openness was protective among the ε4 allele carriers, whereas high agreeableness was protective among non-carriers of the ε4 allele (Terracciano et al., 2014).