Memantine hydrochloride is primarily used in the treatment of moderate to severe Alzheimer's disease. It works by regulating the activity of glutamate, a key neurotransmitter in the brain, which helps to improve memory, attention, reason, language, and the ability to perform simple tasks. By blocking excessive glutamate activity, it protects nerve cells from damage, slowing the progression of symptoms associated with Alzheimer's. Additionally, it is sometimes prescribed for other forms of dementia or cognitive impairment, though its efficacy in these conditions may vary. The medication is typically administered orally and is often used in combination with other treatments to enhance overall therapeutic outcomes.