Alzheimer's disease is the leading
cause of decline in mental abilities (dementia).
Alzheimer's usually affects
aging adults. The disease is uncommon in people younger than 65 and is rare
before the age of 45. Close to half of the people with the disease are between
the ages of 75 and 85.
A rare, inherited form of the disease may
affect some people as early as their 40s. This is called autosomal dominant
Alzheimer's disease or early-onset Alzheimer's.