Acetylcholine (ACh), a widely distributed neurotransmitter in the body known to improve cognition, is reduced in patients with AD; in fact, the increase in the ACh level induced by the use of acetylcholinesterase inhibitors (e.g., donepezil, rivastigmine, and galantamine) has been associated with improved cognitive ability [42,43,44,45]. The gene discussed is ACHE; the disease is Alzheimer disease.