ALDH7A1 and Alzheimer disease: Results of AD-related changes in phospholipid metabolites are mixed, as 7 studies have reported alterations in PME, PDE, or PME/PDE (Brown et al., 1989; Pettegrew et al., 1994; Cuénod et al., 1995; Gonzalez et al., 1996; Mecheri et al., 1997; Forlenza et al., 2005; Mandal et al., 2012), whereas 6 have reported no change (Bottomley et al., 1992; Brown et al., 1993; Murphy et al., 1993; Smith et al., 1995; Rijpma et al., 2018; Das et al., 2021).