APP and Alzheimer disease: Increasing evidence suggests that cholesterol levels may play an important role in AD development; specifically, low levels of HDL and elevated levels of LDL and total cholesterol are associated with increased risk for neurodegenerative diseases due to alterations in APP and Aβ accumulation, whereas high HDL levels offer protection (Kuo et al., 1998; Yaffe et al., 2002; Wolf et al., 2004; Eckert et al., 2010; Williamson and Sutherland, 2011; Gamba et al., 2012; Li et al., 2012; Posse de Chaves, 2012; Maulik et al., 2013).