Alzheimer's Disease Health Center
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Types of Alzheimer's Disease
There are three known types of Alzheimer’s disease. They include:
-
Early-onset Alzheimer's. This is a rare form of Alzheimer's disease
in which people are diagnosed with the disease before age 65. Less than 10% of
all Alzheimer's disease patients have this type. Because they experience
premature aging, people with Down syndrome are particularly at risk for a form
of early onset Alzheimer's disease. Adults with Down syndrome are often in
their mid- to late 40s or early 50s when symptoms first appear.
Younger people who develop Alzheimer's disease have more of the brain abnormalities that are associated with it. Early-onset Alzheimer's appears to be linked with a genetic defect on chromosome 14, to which late-onset Alzheimer's is not linked. A condition called myoclonus -- a form of muscle twitching and spasm -- is also more commonly seen in early-onset Alzheimer's than in late-onset Alzheimer's. -
Late-onset Alzheimer's. This is the most common form of Alzheimer's
disease, accounting for about 90% of cases and usually occurring after age 65.
Late-onset Alzheimer's disease strikes almost half of all people over the age
of 85 and may or may not be hereditary. Late-onset dementia is also called
sporadic Alzheimer's disease.
- Familial Alzheimer's disease (FAD). This is a form of Alzheimer's disease that is known to be entirely inherited. In affected families, members of at least two generations have had Alzheimer's disease. FAD is extremely rare, accounting for less than 1% of all cases of Alzheimer's disease. It has a much earlier onset (often in the 40s) and can be clearly seen to run in families.
WebMD Medical Reference
Reviewed by
Jon Glass on June 16, 2009
© 2009 WebMD, LLC. All rights reserved.
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Common Treatments for Alzheimer’s Disease
