APOE and Alzheimer disease: Although APOE status is a risk factor for AD (Caselli et al., 2009; Ossenkoppele et al., 2013; Strittmatter, Saunders, et al., 1993), many other processes are involved in causing dementia, so the difference between APOE‐ε4 carriers and noncarriers may be a relatively small AD‐related effect on the brain network.