Mouse models of amyloid and tau pathologies, HD, and MJP (Sca3) were shown to have a decrease in the levels of Cyp46a1 mRNA and protein, thus confirming a decrease in CYP46A1 expression in patients with AD, HD, and Sca3 (Hudry et al., 2010; Burlot et al., 2015; Boussicault et al., 2016; Kacher et al., 2019; Nobrega et al., 2019). Here, MAPT is linked to Huntington disease.