That number will likely increase to at least seven million by the early 21 st century unless researchers find a cure or a way to prevent the disease. Age is clearly the major risk factor for Alzheimer's disease. While only five percent of those over 65 have the disease, nearly half the population over 85 have it. Genetics also appears to play an important role. The course of Alzheimer's disease varies tremendously, but is always progressive.
Symptoms usually begin with memory loss, especially of recent events.
For instance, the person will repeat stories in the same conversation. In the early stages, Alzheimer's patients cannot learn new information. The symptoms may include misplacing objects or becoming lost in familiar neighborhoods. As the disease progresses, people with Alzheimer's disease become increasingly confused and disoriented. Another common symptom is personality and behavioral changes such as unusual agitation, depression, and paranoia.