The enzymatic activity of AChE was found to be enhanced within and around amyloid plaques in the brain of AD patients (Ulrich et al. 1990; Morán et al. 1993), increasing the neurotoxicity of Aβ fibrils (Alvarez et al. 1998), and leading to a higher breakdown of ACh in the brain, that is, total reduction of ACh in the brain and the demise of the neuron. Here, ACHE is linked to Alzheimer disease.