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Encore: Scientists look to people with Down syndrome to test Alzheimer's drugs


Alzheimer's disease poses a major threat to people with Down syndrome. Many develop the disease in their 40s and 50s, and most will get it if they live long enough. People with Down syndrome may help researchers find treatments for Alzheimer's, as NPR's Jon Hamilton reports.

JON HAMILTON, BYLINE: Frank Stephens is an actor, a writer and an advocate for people with Down syndrome.

FRANK STEPHENS: I am a man with a very good life. I have a beautiful girlfriend.

HAMILTON: Stephens, who is 40, also has a major concern. His mother is in the late stages of Alzheimer's.

STEPHENS: She is now - almost childlike now. It's very hard to see.

HAMILTON: And as a person with Down syndrome, Stephens is aware that he is likely to develop Alzheimer's himself. So he raises money for Alzheimer's research through the Global Down Syndrome Foundation, and he's part of a research effort called the Human Trisome Project.

STEPHENS: I did take a blood test. I took it to see whether or not I may end up with Alzheimer's.

HAMILTON: Stephens' goal is to help scientists find a drug that can defeat Alzheimer's.

STEPHENS: That would be amazing. And I hope that not only people with Down syndrome can take it, but also people without Down syndrome can take it, too. And I'm hoping I can do that for my mother.

HAMILTON: People with Down syndrome carry an extra copy of chromosome 21. That causes intellectual disability. It also changes the brain in at least two ways that can lead to Alzheimer's.

JOAQUIN ESPINOSA: People with Down syndrome give us a unique opportunity to understand what modulates the severity and the progress of Alzheimer's disease.

HAMILTON: Joaquin Espinosa directs the Linda Crnic Institute for Down Syndrome in Aurora, Colo. He says people with the condition have a hyperactive immune system that protects them from some cancers but also leads to chronic inflammation.

ESPINOSA: And of importance to Alzheimer's, they have brain inflammation across the lifespan.

HAMILTON: There's growing evidence that brain inflammation plays an important role in Alzheimer's. So Espinosa and a team of researchers are looking for ways to keep the brain's immune system in check.

ESPINOSA: We are running clinical trials for immune modulating agents in Down syndrome. So there is an active trial right now to turn down that response with a class of drugs known as JAK inhibitors.

HAMILTON: That's J-A-K. JAK inhibitors are used to reduce inflammation in the joints of people with rheumatoid arthritis. Espinosa hopes these drugs can do the same thing in the brain and cut the risk of Alzheimer's. So he's trying the approach in people with Down syndrome.

Another team at the Crnic Institute is taking a different approach to modulating the immune system. Dr. Huntington Potter says the idea is to boost a special immune cell found in the brain.

HUNTINGTON POTTER: And its job is to eat up things that aren't supposed to be there, like amyloid.

HAMILTON: Amyloid is the sticky substance that builds up in the brains of people with Alzheimer's. And that's the second reason people with Down syndrome are vulnerable to the disease. The extra chromosome they carry causes the brain to produce extra amyloid. Potter hopes to counter this with a drug called leukine, which increases the immune cells that eat amyloid. Last year, he did a small study to establish that leukine could safely be given to people with Alzheimer's.

POTTER: We did not expect to see a cognitive benefit. But three weeks of treatment of leukine, and the individuals actually improved in their cognition.

HAMILTON: Those people didn't have Down syndrome. But Potter says in March, his team showed that leukine also worked in mice that did have Down syndrome.

POTTER: That then allowed us to apply for a grant to study leukine in young adults with Down syndrome before they get Alzheimer's disease.

HAMILTON: They got the grant. Now they're preparing to recruit young adults with Down syndrome. Lina Patel, a psychologist at the Crnic Institute, is confident that people will enroll in the study.

LINA PATEL: The self-advocates that we work with really are proponents because I think that they do see that it is directly impacting their lives.

HAMILTON: And the lives of others. The scientists expect to know whether leukine works in the next five years or so.

Jon Hamilton, NPR News. Transcript provided by NPR, Copyright NPR.

John Hamilton