Alzheimer's disease is a chronic neurodegenerative disease that usually starts slowly with memory loss and difficulty recalling recent events. Over time, symptoms worsen and later stages involve problems with daily living. There are three main phases - mild, moderate, and severe - with increasing memory loss, confusion, and dependence on others for care. While exercise may benefit daily living activities, current treatments only temporarily improve symptoms and do not stop or reverse the progression of the disease. Alzheimer's risk increases after age 65 and is caused by a combination of genetic, lifestyle, and environmental factors.