Except for cathepsin D, these proteins showed a significant decline compared to normal controls, either in AD, in pre-clinical AD, or in longitudinal studies (Goetzl et al., 2015b, 2016a; Abner et al., 2016; Winston et al., 2016, 2018; Agliardi et al., 2019; Jia et al., 2021; Chi et al., 2022). This evidence concerns the gene CTSD and Alzheimer disease.