As they age, those affected by Down syndrome have a greatly increased risk of developing a type of dementia that's either the same as or very similar to Alzheimer's disease. Down syndrome — also known as trisomy 21 — is a condition in which a person is born with extra genetic material from chromosome 21, one of the 23 human chromosomes. Most people with Down syndrome have a full extra copy of chromosome 21, and so they have three copies instead of the usual two. Scientists think the extra copy results from a random error in the specialized cell division that produces eggs and sperm. Researchers have so far identified more than genes on chromosome 21, and they expect to find more. Down syndrome nearly always affects learning, language and memory, but its impact varies from person to person.
Down syndrome often comes with intellectual and developmental disabilities, and patients are at risk for a number of health issues. Sticky clumps of that very same protein accumulating in the brain is a well-known characteristic of Alzheimer's, Hithersay added. That said, many will. In fact, the study team found that 70 percent of the Down syndrome patients who died during the 5. And "we found that people who had two or more other health conditions developed dementia earlier," Hithersay added. Fifty years ago, life expectancy was typically just 10 years among Down syndrome patients, the researchers said. Often, deaths occurred within the first year, as a consequence of congenital heart defects.
November 28, Clinical trials for preventing Alzheimer's disease in people with Down syndrome may soon be possible thanks to new research from King's College London. The researchers found changes in memory and attention are the earliest signs of Alzheimer's in Down syndrome, and these changes start in the early 40s.
Skip to site alert. Skip to content. The early buildup occurs because people with Down syndrome carry an extra copy of chromosome 21, which contains a gene that produces a protein that is a precursor for amyloid. However, there is wide variation in age at onset of dementia, ranging from under 40 to over 70 years of age, suggesting that additional genetic, biological, and environmental factors may be important modifiers of risk that accelerate or slow disease progression.