Down syndrome is a genetic disorder that affects about one in every 800 live births in Canada. It is the most common genetic cause of severe learning disabilities in children and can cause developmental delays, learning difficulties, health issues and some physical abnormalities.
People with Down syndrome have an extra copy of the 21st chromosome. Because of recent medical advances, people with Down syndrome are living longer, usually into their 50’s.
The incidence of Alzheimer’s disease in people with Down syndrome is about three to five times greater than the general population. As with Alzheimer’s disease, the risk increases with age.
The link between Alzheimer’s disease and Down syndrome lies in the 21st chromosome. The protein that leads to the development of plaques in the brain, a hallmark characteristic of Alzheimer’s disease, is located on that chromosome. Since people with Down syndrome have an additional copy of the 21st chromosome, they are prone to an over-production of the protein. Not everyone with Down syndrome, however, develops Alzheimer’s disease.
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Source: Mayo Clinic & Alzheimer Society UK - Last Updated 12/07/13