CYP46A1 activation could be beneficial for AD, HD and other polyglutamine diseases (Scas), in which either brain levels of CYP46A1 or 24HC are decreased (Boussicault et al., 2016; Testa et al., 2016; Nobrega et al., 2019) and, hence, can affect the NMDAR function (Zhou and Sheng, 2013). The gene discussed is CYP46A1; the disease is Alzheimer disease.