BACE1 and Alzheimer disease: Studies have confirmed that as AD worsens, Aβ expression increases and Aβ oligomers inhibit the activation of the PI3K/AKT signaling pathway, leading to a gradual decrease in the phosphorylation expression levels of PI3K subunits and Akt, further causing an increase in BACE1 and PS1 expression, forming a vicious cycle [44].