Last month, the “Take Charge of Your Health Today” page discussed Alzheimer’s disease. This month, we are going to dig a little deeper and talk about how common the disease is in a certain population—people with Down syndrome.
As presented last month, Alzheimer’s disease is the most common form of dementia. Dementia describes symptoms of memory loss and the loss of other cognitive and functioning abilities that are serious enough to affect everyday life. Though researchers do not know exactly what causes Alzheimer’s disease, it is characterized by abnormal deposits of proteins in the brain called amyloid plaque and tau tangles. It is a disease that gets worse over time, leading to breakdowns in a person’s ability to think and move and, eventually, to death. There is no cure for Alzheimer’s.
Down syndrome is caused by an extra copy of chromosome 21, one of the 23 human chromosomes. Instead of the usual two copies, one from each parent, a person with Down syndrome has three copies of chromosome 21. Chromosomes carry genes that tell the body how to build proteins. Proteins determine what a body looks like and how it functions. Though researchers do not know how, the extra genetic material causes people with Down syndrome to have developmental and certain health problems.
The gene that codes for the production of amyloid is on chromosome 21. Because people with Down syndrome have an extra copy of that chromosome, researchers believe they are producing much more amyloid than people who do not have Down syndrome. This is one of the reasons that people with Down syndrome have a much higher risk of developing Alzheimer’s disease.
“All brains make amyloid,” says Benjamin L. Handen, PhD, professor of psychiatry, University of Pittsburgh School of Medicine. “The body is typically able to eliminate it. But if the body is making a lot more amyloid, the amyloid will eventually overwhelm the system. On brain scans of people with Down syndrome who are age 40 and older, we see that most of them have measureable amyloid—levels that are more like people in their 70s and 80s in the general population.”
“About 75 percent of people with Down syndrome who are 60 and older have Alzheimer’s,” says Peter D. Bulova, MD, associate professor of medicine at the University of Pittsburgh, and director, University of Pittsburgh Adult Down Syndrome Center. “But some will start showing symptoms of the disease in their 40s.”
Drs. Bulova and Handen are currently looking for people with Down syndrome willing to volunteer for a study using advanced imaging testing to detect early stages of Alzheimer’s disease. By using brain imaging and other tests, they want to find out if there is some way to predict who will get the disease—or why some people have so much amyloid but are not showing any symptoms.
“We’re hoping this study is one of the first steps in coming up with a prevention for Alzheimer’s disease for both people with Down syndrome and the general population,” says Dr. Bulova. “This is a disease that, by the time people are diagnosed, it’s very progressed. Yet, some of the causes of the disease, such as amyloid deposits, began 15 years before we see any symptoms. So, we hope this study will help us to identify people at a much earlier age. If we could intervene much earlier in the disease process, we’d have a better chance of preventing it.”
Drs. Bulova and Handen are looking for volunteers with Down syndrome who are 25 and older. They are also looking for volunteers who are not showing any signs of having Alzheimer’s disease. And, because researchers know that African Americans have a greater risk of developing Alzheimer’s disease, the doctors would like to have a diverse pool of participants.
“Much of the information we have about Alzheimer’s disease is generalized from research participants who are white. We’d love to change that,” says Dr. Handen.
Dr. Bulova points out that this study is part of a multi-site study and is probably one of the largest studies of Down syndrome that has been funded by the government. The results of the study may help not only people with Down syndrome but all populations.
“People with Down syndrome offer so much to the world,” he says, “and participating is a valuable way to contribute to helping everyone’s overall health. We want people with Down syndrome to have a voice in research, and this is a great opportunity.”