While alterations in either PME and PDE have been reported in AD (Brown et al., 1989; Cuénod et al., 1995; Mecheri et al., 1997; Forlenza et al., 2005; Mandal et al., 2012), most studies have reported no differences between healthy controls and AD patients (Brown et al., 1989, 1993; Bottomley et al., 1992; Smith et al., 1995; Gonzalez et al., 1996; Rijpma et al., 2018; Das et al., 2021). This evidence concerns the gene ALDH7A1 and Alzheimer disease.