Why are people with Down syndrome at greater risk for developing Alzheimer’s disease?

Why are people with Down syndrome at greater risk for developing Alzheimer’s disease?

Scientists believe the increased risk is due to the extra chromosome, chromosome 21, that causes Down syndrome. Persons born with Down syndrome have three copies (instead of the normal two copies) of this chromosome. Scientists have identified several genes on chromosome 21 that are responsible for certain aspects of the aging process. They believe the extra full or partial chromosome contributes to the increased risk of Alzheimer’s disease seen in people with Down syndrome. In addition, genes on chromosome 21 produce a key protein, amyloid precursor protein, which plays an important role in the brain changes that are specifically seen in Alzheimer’s patients.