The “Cholinergic Hypothesis of Alzheimer’s Disease” [13] proposed by Perry at al. in 1999 links the dysregulation of the basal forebrain cholinergic neurotransmission, alteration in the levels of cholinergic markers such as Ach, choline, and ChAT, to the age-related cognitive functions’ decline with AD. The gene discussed is CHAT; the disease is Alzheimer disease.