In late November, Contrarian reported that researchers at Stanford University had used a drug therapy to improve the learning skills of mice with a form of Down syndrome. Jenn Power, community leader at L’Arche Cape Breton and mother of twin boys with Down’s, found the research distressing. She said people with Down’s don’t need a cure; they need “a society that values what they have to offer.” This produced a fascinating discussion with many thoughtful contributions on all sides of the issue.
At Contrarian‘s request, Dr. Ahmad Salehi, M.D., Ph.D., the lead researcher on the Stanford University study, has responded to our discussion in an equally thoughtful spirit.
First of all, I would like to thank you for a quite accurate description of our recent study on the mouse models of Down syndrome. In this study, we found that some aspects of cognition could be restored in mouse models of Down syndrome using a pro-drug.
For the last 10 years, the primary goal of our Down syndrome research at Stanford University has been to understand the molecular mechanisms of cognitive dysfunctions in people with Down syndrome. Our recent study has brought us a little closer to understanding cognition in a mouse model of Down syndrome.
In response to Jenn (see posts here and here), I would like to point out that restoring a rather limited aspect of learning and memory in a mouse model of Down syndrome is far from being a cure. It is a very small step toward understanding how the brain works and how we can potentially restore dysfunction found in the brain of mouse models of Down syndrome. The goal of our research is not to change the personality of a person with Down syndrome, but rather to help them lead more independent lives.
There are many aspects of people with Down syndrome that we should consider a blessing. Their positive interactions with others, their cheerfulness and affection, and their nonjudgmental attitude are just a few examples. The question whether all people with Down syndrome need some kind of treatment is entirely personal and completely depends on the individual situation. Nevertheless, not every child with Down syndrome is as lucky as Jenn’s children. There are many places in the world that may not look at Down syndrome the way that Jenn does. For these children, finding a way to even partially restore cognition or preventing further deterioration in their learning and memory would be extremely important and helpful in their very competitive societies.
One other concern that I heard recently is about the fact that Down syndrome is a chromosomal disorder and that there is no way to remove the extra chromosome from every cell. Although this is indeed the case, we may not need to remove the entire extra chromosome 21 to counter the cognitive dysfunction associated with Down syndrome. Our previous work has shown that indeed there are a few genes on chromosome 21 whose overexpression could be linked to dysfunction of several brain areas in mouse models of Down syndrome. This means that finding a way to reduce the expression of these genes in the future could be a fundamental treatment for certain aspects of Down syndrome.
Thanks to advances in medical treatment and inclusion in society, people with Down syndrome live longer than ever before. Although this is good, it brings its own challenges. People with Down syndrome on average age faster and are at a much higher risk of developing dementia and early-onset Alzheimer’s disease. After the age of 40 years, the brains of people with Down syndrome look very similar to those of people with Alzheimer’s disease. The task for us is to find out how to prevent adults with Down syndrome from converting to Alzheimer’s disease later in their lives. There are at least 350,000 people with Down syndrome just in the US. Preventing even a fraction of this rather large group from developing Alzheimer’s disease is an important health issue.
I do believe that we should avoid giving false hope to people with Down syndrome and their families. But the only thing that keeps us going as parents and as researchers is the hope that one day, our children will live free of problems that are within our reach to somehow resolve.
(Sietske N. Heyn. Ph.D., also contributed to this post.)