It is still unclear what exactly causes Alzheimer's disease. Changes in the brain may begin years before symptoms appear as neurons die or lose connections while abnormal deposits of the proteins amyloid and tau build up in the brain. Certain genetic variations and a family history of Alzheimer's have been associated with increased risk, especially in people with early-onset Alzheimer's. For most people, however, genes alone do not appear to be the determining factor. Some lifestyle factors may help lower the risk of developing Alzheimer's, such as healthy diet, exercise, adequate sleep, social engagement, and mentally stimulating pursuits.

Some of the earliest signs of Alzheimer's tend to be problems with memory but as the disease spreads, other parts of the brain become affected. Eventually, people may experience personality and behavioral changes, fail to recognize loved ones, and lose the ability to perform basic tasks or care for themselves. Although there is currently no cure, early detection and intervention can be important in managing disease progression, improving quality of life, and planning for future care. Researchers are still working to find more therapeutic options for people with this debilitating disease.