APOE and Alzheimer disease: While previous studies have explored ApoE ε4-dependent changes in subjects with AD and MCI, these studies have largely been cross-sectional (Drzezga et al., 2005; Hirono et al., 2002; Matsuda, 2001; Reiman et al., 1996; Roher et al., 2012; Scarmeas et al., 2004).