MAPT and Alzheimer disease: Increasing evidence has suggested that a complex interaction exists between the cholinergic system and pathological features of AD, whereby amyloid-β (Aβ) can be toxic to cholinergic neurons and cholinergic dysfunction may promote Aβ deposition and tau pathology in ways that contribute to cognitive impairment (Hampel et al., 2018, Ramos-Rodriguez et al., 2013, Schliebs, 2005).