SCOTT DETROW, HOST:
Some of the most important research on Alzheimer's disease is powered by altruism.
JUNE WARD: It's not for us, but it's for my sister's children and their children so that they won't have the same nothing to choose from.
DETROW: NPR's Jon Hamilton reports on an international network of families with an inherited form of Alzheimer's. The network has allowed scientists to make key discoveries yet faces an uncertain future amid cuts in federal funding.
JON HAMILTON, BYLINE: The families carry rare gene mutations that cause Alzheimer's in middle age or even earlier. June Ward and her sisters found out when a cousin started having memory problems in her 50s and decided to get her genes tested.
WARD: It was always in our peripheral vision and finding out that our cousin had the gene mutation made it right up in front of our face, so that we knew what it was and we knew what the odds were that we would be impacted by the disease personally.
HAMILTON: Those odds - 50/50 for each sibling. Ward and her sisters wanted to do something, so they joined the Dominantly Inherited Alzheimer's Network, or DIAN. It involves more than 200 families in 10 countries.
WARD: And so now we're doing what we can do, which is to participate in the drug trials and try to take what action we can toward a better future.
HAMILTON: DIAN is run by WashU Medicine in St. Louis. Dr. Randall Bateman, the network's codirector, says DIAN families offer a unique window on Alzheimer's.
RANDALL BATEMAN: These families that carry these mutations is still the only population in the world where we not only have certainty over whether they will get it, but when they will get it.
HAMILTON: If a family member inherits a mutation from either parent, dementia is all but inevitable. The specific mutation determines whether symptoms appear in a person's 30s or not until their 60s. Bateman began studying affected families in the early 2000s. He was trying to understand what causes the protein amyloid to appear in the brains of people with Alzheimer's.
BATEMAN: And it was clear to me that these people with these mutations could really answer that question.
HAMILTON: But the mutations are so rare that no single research center had enough family members for a large study. So in 2008, the National Institutes of Health began funding DIAN to create a common pool of participants. Bateman says the multimillion-dollar investment has paid off. For example, he says, it was brain scans of DIAN family members that allowed scientists to discover how Alzheimer's begins.
BATEMAN: Before the first memory loss is noticed, there is this 20-year period where changes are occurring in the brain, and they're leading up to that first symptom onset that then leads to dementia and disability and ultimately death.
HAMILTON: In 2012, DIAN added a clinical trials unit for potential Alzheimer's drugs. It's a partnership with the Alzheimer's Association and pharmaceutical companies. Bateman says this has given companies a way to test their drugs in people who are destined to get the disease.
BATEMAN: Our ability to be able to determine what the effects of these treatments are is really powered by that certainty.
HAMILTON: Early studies of DIAN families showed that certain drugs could reduce amyloid in the brain, and a study in 2025 suggested that doing so could delay symptoms of the disease. DIAN scientists have also discovered a few people who carry a mutation but appear to be protected from dementia. One of them is Doug Whitney, who spoke with NPR last year.
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DOUG WHITNEY: Well, I'm 75 years old, and I think I'm functioning fairly well. I'm still not showing any of the symptoms of Alzheimer's.
HAMILTON: Scientists have been studying Whitney to figure out why, and he's been eager to help.
WHITNEY: I guess I'm kind of special (laughter). But, you know, I told the researchers, if you need me, I'll be here.
HAMILTON: Some DIAN family members do more than just participate in research studies. Take Lindsay (ph), who asked that we use only her first name in order to frankly discuss her family's medical history. Lindsay's father was diagnosed with Alzheimer's when he was 48 and she was 18.
LINDSAY: To have the strongest, smartest person in your life all of a sudden be taken by something so terrible to the point where he can't speak, to the point where he doesn't know who you are - there's no words to describe what that experience is like.
HAMILTON: Lindsay responded by immersing herself in the science.
LINDSAY: I went to our local library, and I checked out every single book on Alzheimer's disease because I was like, there's got to be something we can do.
HAMILTON: There wasn't. Lindsay started taking science courses in college. Then she joined DIAN, even though that meant several days of uncomfortable tests.
LINDSAY: I got a lumbar puncture. I got an MRI scan. I got a PET scan. I got lots and lots of blood collected from me. I did cognitive testing, neurological testing - the whole nine yards.
HAMILTON: Including a genetic test, though, at the time, Lindsay chose not to see the result. She just kept studying.
LINDSAY: Well, now I have a Ph.D. in neuroscience, and I work in an Alzheimer's disease lab.
HAMILTON: Lindsay eventually learned that she does not carry the early Alzheimer's mutation. Yet she continues to attend the annual meeting of DIAN families and to help run a nonprofit for those families called Youngtimers.
Dr. Tammie Benzinger, a radiologist at WashU Medicine, says DIAN does provide benefits to people who join the network. They gain access to world-class experts and get to meet other members of affected families. But participants also undergo extensive and repeated testing, and Benzinger says those who volunteer for drug trials run the risk of side effects like swelling or bleeding in the brain.
TAMMIE BENZINGER: It's an incredible contribution, especially if you think about the fact that these are young people. They still have jobs. They have young children.
HAMILTON: Benzinger says DIAN families helped make amyloid drugs a reality. Two are now on the market, and she says the DIAN network has played an important role in assessing the side effects of this class of drugs.
BENZINGER: What we've seen with the amyloid therapies is how important this DIAN cohort is. And for the next therapies to come forward, I think we really need this network to continue operating.
HAMILTON: That's not a certainty. After the Trump administration took over in 2025, WashU was asked to reduce its DIAN funding request by more than one-third. Benzinger says deeper cuts could cause major damage.
BENZINGER: The network that's been built up, the years that have gone into the training and the relationships - without funding, all of that would fall apart.
HAMILTON: Right now, DIAN is getting by with temporary funding from the NIH. That money came after Lindsay and other family members rallied around the network.
LINDSAY: We got 600 signatures in three days that were then sent to the NIH advisory board.
HAMILTON: Lindsay is encouraged that Congress continues to vote in support of Alzheimer's research. Even so, it remains unclear what will happen to the federal grants that have supported DIAN. Lindsay says she's trying to remain optimistic.
LINDSAY: I'm still that naive 18-year-old girl thinking that she can cure her dad. Obviously, I didn't, or he would be sitting next to me right now.
HAMILTON: A cure remains far away, but Lindsay says there's growing evidence that amyloid drugs, if given early enough, can delay symptoms of the disease in people who carry the mutation.
LINDSAY: I 100% believe that the first survivor of Alzheimer's will be from this community.
HAMILTON: Assuming the community itself can stay intact. Jon Hamilton, NPR News.
(SOUNDBITE OF DE LA SOUL SONG, "MEMORY OF... (US)") Transcript provided by NPR, Copyright NPR.
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