Alzheimer's is a chronic neurodegenerative disease that usually starts slowly and worsens over time, causing short-term memory loss and difficulties with language, mood, motivation, and self-care. It is caused by changes in the brain and primarily affects those over 65. While there is no cure, regular mental and physical activity may help prevent Alzheimer's or slow its progression, and specific medicines, nutrition, exercise, and an adapted environment can help manage symptoms.