Dementia affects memory and thinking enough to interfere with normal daily activities. About 1 out of every 10 Americans older than 65 years has some degree of dementia. Poor memory alone is not dementia, and some declines in short-term memory are normal as people age. Several conditions can cause dementia, but the 2 most common diseases are Alzheimer disease and cerebrovascular disease. In Alzheimer disease, build-up of abnormal proteins damages brain cells. In cerebrovascular disease, low blood flow to the brain damages brain cells. There is no cure for dementia. However, the U.S. Food and Drug Administration has approved 5 drugs that can modestly slow the worsening of dementia in some patients. Four of them belong to a class of drugs called cholinesterase inhibitors (donepezil, galantamine, rivastigmine, and tacrine). The fifth drug, memantine, belongs to a class of drugs called neuropeptide-modifying agents. These drugs cannot cure dementia, can be costly, and can have side effects. It is uncertain how they can best be used to improve health outcomes for people with dementia.