CHRM1 and Alzheimer disease: Dramatic loss of cholinergic neurons located in the basal forebrain increased levels of α7 nicotinic acetylcholine receptor (α7 nAChR) (Ikonomovic et al., 2009; Marutle et al., 2013) and decreased levels of M1 muscarinic acetylcholine receptor (M1 mAChR) (Yi et al., 2020) were found in the cortical regions of human AD brains (Ferreira-Vieira et al., 2016).