UK researchers explore the relationship between Down syndrome and Alzheimer's disease

Down syndrome remains the most common chromosomal condition diagnosed in the United States. Each year, about 6,000 babies born in the United States have Down syndrome, meaning it occurs in about one in every 700 babies.

People around the globe will join together on March 21 to raise awareness for the condition. World Down Syndrome Day has been officially observed by the United Nations since 2012. The 21st day of the third month (March) was selected to signify the uniqueness of the triplication (trisomy) of the 21st chromosome which causes Down syndrome.

Thanks to medical advances, people with Down syndrome are living longer and fuller lives; however there is still much to learn about the Down syndrome brain. This includes why those with the genetic condition are more likely to be diagnosed with Alzheimer’s disease as they age, and why it seems the memory disease appears earlier in life.

“We are seeing Alzheimer’s pathology in people with Down syndrome in the age range of 40 to 45 years old, whereas the same Alzheimer’s pathology is typically seen in the general population in the 70 to 75 age range,” said Frederick Schmitt, Ph.D., professor of neurology in the University of Kentucky College of Medicine and researcher at the UK Sanders-Brown Center on Aging. Researchers involved in this work have discovered that people with Down syndrome show signs of Alzheimer’s brain pathology by the time they are 20, and that virtually all of them have this brain pathology by the time they reach 40.

Schmitt has been involved in research regarding Down syndrome for more than four decades. “We’ve known for many, many years that the genetic makeup of people with Down syndrome leads to overproduction of beta amyloid in the brain. That’s why we say it’s one of the three genetic forms of Alzheimer’s,” said Schmitt. Alzheimer’s is characterized by the buildup of a protein called beta amyloid, which forms sticky plaques on the brain and can cause brain cells to die.

“The potential connection between Down syndrome and Alzheimer’s disease seemed to be ignored for a while until people living with Down syndrome started aging,” said Schmitt.

Now that people with Down syndrome are living into their 50s, 60s and even later, researchers can track disease progression and more.

UK has been part of this research for more than a decade now. The work originally started thanks to a grant from the Eunice Kennedy Shriver National Institute of Child Health and Human Development in 2009 and was initially aimed at looking at how connections change in the brain over time. A focus was then put on narrowing this work to look at brain inflammation and brain blood vessel changes in people living with Down syndrome.

To continue research in this area, the Alzheimer Biomarkers Consortium-Down Syndrome (ABC-DS) was formed by the National Institute on Aging. ABC-DS is a longitudinal study with a goal of following adults with Down syndrome over time to identify early biomarkers that may represent the onset of Alzheimer's. UK is one of eight clinical sites for this study. Investigators hope that these biomarkers can be useful to inform clinical trials and improve the quality of life in people with Down syndrome and for the general population.

Through their ongoing work, the team at UK has now worked with and monitored more than 120 people living with Down syndrome.

“As a researcher, the goal is always to hopefully benefit a population and to be able to make meaningful changes for those individuals," said Amanda Glueck, Ph.D., assistant professor of neurology in the UK College of Medicine. "There is not a better population than our families. They’re absolutely wonderful. They’re so invested in the project, and they want to help just not their own family but the Down syndrome community as a whole. It is really beautiful."

Holly and Jeremy Thompson are part of that cohort at UK, joining the research team in their work about a decade ago.

“Jeremy was born in 1988 with Down syndrome and we’ve been involved in studies from early on for different things,” said Holly Thompson.

Jeremy enjoys keeping a very busy schedule — participating in multiple events with the Special Olympics and serving on their Athletic Leadership Council. He also just last year became the first individual in the country with Down syndrome to become a certified member of FEMA’s Community Emergency Response Team (CERT).

He also dedicates some of his busy schedule, along with his family’s, to helping others better understand the condition he is living with by participating in studies like the one at UK.

“Since the life expectancy of an individual with Down syndrome has dramatically increased, we really don't know what to expect as they age. And from a parent’s perspective I want to better understand what I can look for,” said Thompson. “So, when given an opportunity to help add to that body of knowledge about this disease, it was something we couldn’t pass up. We may not benefit from it, but maybe the next kid will or the next kid after that. I firmly believe that’s the only way we improve the lives of individuals with Down syndrome is learning as much as we possibly can.”

With that mindset at the forefront of any research they’ve gotten involved in, Holly feels participating in ABC-DS has already directly benefited their family.

“Just from the conversations that I’ve had with the doctors in the study we knew kind of what to look for," she said. "Jeremy was diagnosed with Alzheimer’s and memory issues. Several years ago, I probably would have just chalked it up to being out of school, it’s the Down syndrome, or other factors, had I not been involved in this. I was able to go back and say, ‘Does this make sense? Is this what we should be looking at?’ They were able to get him on medication, which has really helped him kind of plateau. So even though we got into it not knowing what to expect, and not expecting to get anything out of it … for us we did.”

Participants in the study go through cognitive testing, blood tests and imaging every 16 months. Their visits with the team at UK are a highlight for many of them as well as the researchers.

“Our participants generally enjoy being a very important person for the day. We make it an experience,” said Jordan Harp, Ph.D., assistant professor of neurology in the UK College of Medicine, neuropsychologist at Kentucky Neuroscience Institute, and researcher at the UK Sanders-Brown Center on Aging.

 “It’s absolutely contagious," said Glueck. "They’re walking around with big smiles, they’re giving hugs, and they’re getting hugs from everybody. It is not just everybody on the research team, but because a lot of them have been coming for years they also know a lot of our clinical staff as well.”

The team at UK is hopeful that they can increase the number of VIPs they get to host as part of their work looking at the connections between Down syndrome and Alzheimer’s disease. Currently, there are about 40 people that makeup UK’s ABC-DS cohort. They would like to see that number double. Thompson is hopeful that sharing her family’s journey through participating, other families will be encouraged to get involved.

“For me, it is about learning more about Jeremy and understanding how I can best help him have the best life he can possibly have,” said Thompson.

Helping participants and their families, as well as future generations to come, have the best lives possible is the exact reason the research team at UK got involved in this work and why they are actively working to expand upon it.

“There is a phenomenon in science where initially, you do big studies on the most available people. Historically, we ended up accidentally not giving enough attention to special populations. For too long, Down syndrome has been that special population,” said Harp. “It has been really nice to be a part of an initiative that really takes into account what’s special about the community itself. That high inclusion we’ve talked about, and high interest level from all the parents. If you want to see it, you just go to a community event and it's almost always like a party.”

It is that inclusive atmosphere and contagious positive outlook that has kept Schmitt focused on this work for nearly half a century. “They are extremely precious and outgoing … you can’t ask for a better group of people.”

Schmitt and the rest of the ABS-DS teams are committed to helping those with Down syndrome live longer lives, without the threat of Alzheimer’s and other dementias.

The ABC-DS is funded by the National Institute on Aging (NIA), with additional Down syndrome projects supported through the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), and the National Institutes of Health (NIH) INCLUDE (INvestigation of Co-occurring conditions across the Lifespan to Understand Down syndromE) project.

For more information, please reach out to UK’s Down syndrome study coordinator roberta.davis@uky.edu

Research reported in this publication was supported by the Eunice Kennedy Shriver National Institute of Child Health & Human Development of the National Institutes of Health under Award Numbers R01HD064993 and 2R01HD064993 and the National Institute on Aging of the National Institutes of Health under Award Number U19AG068054. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.