Memantine is used to treat the symptoms of Alzheimer's disease (AD; a brain disease that slowly destroys the memory and the ability to think, learn, communicate and handle daily activities). Memantine is in a class of medications called NMDA receptor antagonists. It works by decreasing abnormal activity in the brain. Memantine may improve the ability to think and remember or may slow the loss of these abilities in people who have AD. However, memantine will not cure AD or prevent the loss of these abilities at some time in the future.