Studies have reported that the protein expression level of CatD is decreased in AD (Urbanelli et al., 2008), and increased CatD activity and expression promoted the fusion of autophagosomes with lysosomes and ultimately contributed to the clearance and degradation of Aβ aggregates and phosphorylated tau (Zhang et al., 2017; Song et al., 2018). Here, MAPT is linked to Alzheimer disease.