This regulation is suggested to be disturbed in AD through two mechanisms i.e., decreased activity of ChAT, and/or increased activity of AChE and BuChE, both of which lead to a low concentration and reduced turnover of ACh in the cholinergic system (Perry et al., 1978; Atack et al., 1986; Giacobini et al., 1989; DeKosky et al., 1992). Here, CHAT is linked to Alzheimer disease.