Several research groups have reported that activation of CYP46A1 activity can ameliorate the symptoms of Alzheimer’s disease (AD) and Huntington’s disease (HD) in animals (Hudry et al., 2010; Chali et al., 2015; Djelti et al., 2015; Boussicault et al., 2016; Mast et al., 2017). This evidence concerns the gene CYP46A1 and Alzheimer disease.