APOE and Alzheimer disease: Although previous studies have already applied the multimodal method for the classification of AD (Zhang et al., 2011; Young et al., 2013; Liu et al., 2014; Ritter et al., 2015; Schouten et al., 2016; Hojjati et al., 2018; Gupta et al., 2019a) with other groups, this study was the first to combine five different types of neuroimage modalities with two APOE genotype scores for the classification of all six binary classification groups (AD vs. HC, MCIs vs. MCIc, AD vs. MCIc, AD vs. MCIs, HC vs. MCIc, and HC vs. MCIs).