The pathogenesis of the disease has been classifiedas the amyloid cascade hypothesis,, the tau hyperphosphorylationhypothesis, and the cholinergic hypothesis,with other contributing links.−,  The cholinergic hypothesis isthe oldest theory on the pathogenesis of AD. This hypothesis has made acetylcholinesterase (AChE) and butyrylcholinesterase(BChE) enzymes a therapeutic target for AD. The gene discussed is MAPT; the disease is Alzheimer disease.