Although there have been contradictory reports on the role of CYP46A1 polymorphism in AD (Papassotiropoulos et al., 2003; Borroni et al., 2004; Helisalmi et al., 2006; Li et al., 2006; Tedde et al., 2006; Kolsch et al., 2009), it has been reported that the CYP46A1 T allele may be a risk factor (He et al., 2012). This evidence concerns the gene CYP46A1 and Alzheimer disease.