There are conflicting reports on the role of CTSB in Aβ toxicity in AD, identifying CTSB as a protective protease by digesting Aβ and reducing its accumulation in the neuronal cells (Mueller‐Steiner et al., 2006; Perlenfein & Murphy, 2017; Wang et al., 2012; Zhou et al., 2020). This evidence concerns the gene CTSB and Alzheimer disease.