APOE and Alzheimer disease: However, no studies have examined either (1) the joint effects of Alzheimer's disease risk factors (Aβ and ApoE ε4) in cognitively normal older adults, which have confounded studies of network function during resting state fMRI in normal aging (Brier et al., 2014) or (2) metabolic connectivity within- and between- canonical ICNs and graph theoretic properties of metabolic brain networks in cognitively normal aging.