Three of the FDA-approved medications for Alzheimer's Disease (AD) are in the same drug class— namely, ??? inhibitors. These drugs work to curb the breakdown of acetylcholine, a chemical in the brain that is important for memory and learning, by inhibiting an enzyme, acetylcholinesterase, that is responsible for the metabolism of acetylcholine; as a result, concentrations acetylcholine increase in the brain and symptomatic improvement is seen.