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Causes of Alzheimer’s Disease

Alzheimer's Disease in People with Down Syndrome

Many, but not all, people with Down syndrome develop Alzheimer’s disease when they get older.Middle aged adult with Down Syndrome

People with Down syndrome are born with an extra copy of chromosome 21, which carries the APP gene. This gene produces a specific protein called amyloid precursor protein (APP). Too much APP protein leads to a buildup of protein clumps called beta-amyloid plaques in the brain. By age 40, almost all people with Down syndrome have these plaques, along with other protein deposits, called tau tangles, which cause problems with how brain cells function and increase the risk of developing Alzheimer’s dementia.

However, not all people with these brain plaques will develop the symptoms of Alzheimer’s. Estimates suggest that 50 percent or more of people with Down syndrome will develop dementia due to Alzheimer’s disease as they age. People with Down syndrome begin to show symptoms of Alzheimer’s disease in their 50s or 60s.

This type of Alzheimer’s is not passed down from a parent to a child.

Down Syndrome and Alzheimer's Research

Scientists are working hard to understand why some people with Down syndrome develop dementia while others do not. They want to know how Alzheimer’s disease begins and progresses, so they can develop drugs or other treatments that can stop, delay, or even prevent the disease process.

Research in this area includes:

  • Basic studies to improve our understanding of the genetic and biological causes of brain abnormalities that lead to Alzheimer’s
  • Observational research to measure cognitive changes in people over time
  • Studies of biomarkers (biological signs of disease), brain scans, and other tests that may help diagnose Alzheimer’s—even before symptoms appear—and show brain changes as people with Down syndrome age
  • Clinical trials to test treatments for dementia in adults with Down syndrome

There are many ways to learn about research opportunities

For More Information About Down Syndrome and Alzheimer’s 

Down Syndrome and Alzheimer’s Disease Resources

Down Syndrome Research and Resources

If you are interested in learning more about Alzheimer's & Dementia, please call us at 1-800-438-4380, Mon-Fri, 8:30 am-5:00 pm Eastern Time or send an email to adear@nia.nih.gov