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Down’s Syndrome and Alzheimer’s

Down’s Syndrome and Alzheimer’s
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First Published: Tue, Mar 11 2008. 12 45 AM IST

Updated: Tue, Mar 11 2008. 12 45 AM IST
Researchers at the Byrd Alzheimer's Center and Research Institute in Tampa, Florida, say they have recently learned some important new things about the link between Alzheimer's disease and Down's Syndrome.
Huntington Potter, the centre's CEO, said this link might contain important clues for the two biggest goals of Alzheimer's scientists everywhere: how to detect the disease early on, and how to cure it.
People who are born with Down's Syndrome have some mental impairment and certain distinguishing physical features. The cells in their body contain a characteristic feature, an extra chromosome. Although most people have 23 pairs of chromosomes in each cell, people with Down's Syndrome have an extra version of chromosome 21, a set of three instead of a set of two. These same cells also have been discovered in some people with Alzheimer's disease.
Potter spoke last week with ‘St Petersburg Times’ to explain why this is important:
Why are you studying Alzheimer's disease and Down's Syndrome?
We're studying Alzheimer's disease because there are 450,000 people with the disease in Florida, it costs the economy about $10 billion a year and the problem is getting worse and worse.
The reason we're studying Alzheimer's and Down's syndrome is because every Down's syndrome individual who has three copies of chromosome 21 in every cell of their body develops Alzheimer's disease by the time they're 30 or 40.
What does that connection tell us about Alzheimer's?
The question that came to us some years ago is if Down's Syndrome individuals get Alzheimer's disease, is it possible that Alzheimer's individuals are really Down's Syndrome individuals in disguise? And specifically, is it possible that Alzheimer's patients develop (Down's syndrome) cells over a lifetime, which either causes or at least contributes to their disease?
So, those Down's Syndrome cells may contribute to or cause people to get Alzheimer's symptoms and loss of brain function?
Correct (he explains that the gene for a harmful protein that causes Alzheimer's is contained on chromosome 21, the same one that Down's Syndrome cells have three sets of). And, therefore, if you have three copies of the chromosome instead of only two, you'll have more of this bad protein, and more accumulation and more damage.
So, the production of these Down's Syndrome-type cells is really a step along the way towards actually getting Alzheimer's disease?
Correct. In the study that we've just published, we've discovered that the gene which, when mutant, causes Alzheimer's disease causes the cells to mishandle their chromosomes and become Down's Syndrome, or trisomy 21 cells.
What is the significance of this research?
The significance is that it gives us an insight into the cause of Alzheimer's disease that we didn't have before and that will allow us to develop new therapies and new diagnoses based on the relationship between Alzheimer's and Down's Syndrome.
So, one line of research is to see if you can use those Down's Syndrome cells to detect if a person is in the early stages of Alzheimer's?
Yes, the presence of (Down's Syndrome) cells in a person would be, we hope,...an early indicator of their risk for developing Alzheimer's disease. And current research is being designed to test that idea.
Because right now, there are some people who are clearly going to get it, but you don't know that for sure?
Yes, 10% of people above the age of 65 have Alzheimer's disease, but almost 50% of people over 85 have the disease. Some half of people over 65 are destined to get Alzheimer's disease if they live long enough. They just don't know it yet.
If you could find a way to stop the production of those Down's Syndrome-type cells, what would that mean?
If we could prevent the...generation of trisomy 21 Down's Syndrome cells in an individual, we would prevent them from developing Alzheimer's disease. That's the goal. We don't yet know that's true, but that would be the goal. Or, if we could get rid of them once they're formed, by some magic bullet, then that might be a treatment for Alzheimer's disease.
©2008/By NYT Syndicate
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First Published: Tue, Mar 11 2008. 12 45 AM IST