APOE and Alzheimer disease: Another study reported that ε4 carriers with SMC showed altered AD-related cerebrospinal fluid and fluorodeoxyglucose-positron emission tomography (PET) measures (Mosconi et al., 2008); In addition, they demonstrated that aging, APOE ε4, and SMC were associated with high Aβ burden, indicating that selection based on the presence of SMC and APOE ε4 may help identify healthy elderly participants with high Aβ burden eligible for secondary prevention trials (Zwan et al., 2016).