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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 occurs 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).

 

Recommended Related to Alzheimer's

David Hyde Pierce: Advocate for Alzheimer's Research

David Hyde Pierce's longest-running role to date has been as an advocate for Alzheimer's disease awareness and research. Best known as Niles Crane, the character he played for 11 years on NBC's hit sitcom Frasier (as well as his 2008 Tony for the Broadway musical Curtains), Pierce originally got involved with the Alzheimer's cause for very personal reasons. The disease claimed his grandfather, and his father likely suffered from Alzheimer's disease as well. November is National Alzheimer's...

Read the David Hyde Pierce: Advocate for Alzheimer's Research article > >

 

WebMD Medical Reference

Reviewed by Jon Glass on March 13, 2012
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