APOE and Alzheimer disease: AD is a progressive neurodegenerative disease induced by multiple factors, such as apolipoprotein E genetic risk variants, excessive levels of phosphorylated tau protein, immunoinflammatory responses and Aβ deposition, all of which contribute to AD pathogenesis through the Aβ-dependent pathway (Chen et al., 1996; Yu et al., 2014; Moosavi et al., 2015).