Memantine (brand names include Reyind) is a prescription medication primarily used to treat symptoms of moderate to severe Alzheimer's disease. It works by regulating the activity of the brain chemical glutamate to help improve memory, attention, and the ability to perform daily activities, though it is not a cure for the disease. 

Uses: Memantine is FDA-approved for moderate to severe Alzheimer's disease (AD) and has shown benefit for other dementias like dementia with Lewy bodies. It may be used alone or in combination with cholinesterase inhibitors (another class of AD medication like donepezil).