MAPT and Alzheimer disease: Indeed, ACh dysfunction is one of the first theories linked to AD because MS and cholinergic neurons are particularly vulnerable to tau aggregates and neurodegeneration, both of them influencing the entorhinal–hippocampal processing as we discussed previously (Chen Z. R. et al., 2022; Igarashi, 2023; Salimi-Nezhad et al., 2023).