Moreover, plasma GLP-1 levels decrease in APP23/PS45 mice and negatively correlate with brain Aβ load in AD patients, while an GLP-1R agonist improves cognitive impairment and lowers Aβ/β-CTF by reducing BACE1 expression in the hippocampus/cortex of APP23/PS45 mice (Zhang et al., 2025). Here, BACE1 is linked to Alzheimer disease.