Interestingly, Duan et al. (2022) demonstrated that exogenous synthetic Aβ42 monomers improve memory deficits not only in cDKO mice, which lack Aβ42 deposition, but also in amyloid precursor protein/PS1/Tau triple-transgenic 3×Tg-AD mice, soluble Aβ42 in CSF also decreases in 3 × Tg-AD mice with age (Cho et al., 2016). This evidence concerns the gene APP and Alzheimer disease.