At just 53 years old, Elizabeth [McGuff] was diagnosed with young-onset Alzheimer’s disease. “I [her son, Mike] was in total shock. She was so young. I could never imagine someone getting Alzheimer’s at 53. In fact, I don’t think I even knew such a thing was possible.” She died from complications related to the disease five years later.Alzheimer’s is not just a disease of old age. About 200,000 of the 5.7 million people with the disease have the young-onset form, meaning they were diagnosed before age 65, according to the Alzheimer’s Association. Many people are in their forties and fifties with dependent children and booming careers when the disease strikes. As it does with age-related Alzheimer’s disease, the young-onset form also impacts memory, thinking, behavior, and, in later stages, daily activities and functions.