The study that keeps listening: how U-M built the world’s map of aging
By Eric Shaw
For 34 years the Health and Retirement Study has followed the same 20,000 older Americans. A $195 million renewal, the largest research grant in University of Michigan history, carries it through 2029.
When a participant’s blood work comes back looking wrong, Kenneth Langa, a physician at the University of Michigan, picks up the phone himself.
The person on the other end of the line is someone whose data he has studied for years, a little startled to hear from him, sometimes learning about a health problem for the first time.
“Many of them feel very proud about being part of the study and providing their data, their time and information over 20 or more years,” said Langa, co-director of the Health and Retirement Study. “We obviously couldn’t be doing this work without them.”
That relationship, tended one phone call at a time, is the smallest human unit of a very large machine.
A public laboratory for aging
The Health and Retirement Study has followed the same Americans over the age of 50 for 34 years, roughly 20,000 of them, measuring nearly everything that bears on how a life ages: work and wealth, marriages and moves, memory tests and the proteins in a drop of blood.
In 2024, the National Institute on Aging, a part of the National Institutes of Health, renewed the study with about $195 million in funding, the largest research grant in U-M history. Langa and the epidemiologist Jessica Faul now lead it together at the Institute for Social Research, or ISR.
What that money sustains is less a single experiment than a shared resource.
“We’re really trying to create a public laboratory, with all the data that any researcher would want to understand aging in the United States,” Langa said.
Fewer people at risk, more people affected
The questions it answers are the ones almost no family escapes. It has helped show that the risk of a person developing dementia has been falling for about 25 years, most likely because more people are staying in school longer and because doctors now treat blood pressure and cholesterol better than they once did.
But the study also measured the toll of the disease that remains.
“Spouses can spend up to 50 hours a week just helping someone get through the day,” Langa said.
Because the baby boom generation is so large, he added, the number of people living with dementia keeps climbing even as the risk to any one person falls.
That is part of what makes the study so valuable to policy decisions around topics like Medicare and Social Security – policymakers cannot budget for a future they otherwise couldn’t see. Faul put the point plainly: the Social Security Administration has little sense of who is about to reach retirement age or how ready they are, and the study is often what lets the country look ahead before the bills arrive.
Owned by no single field
The study was built so that no single field decides what it asks. It covers a person’s money, health, family and memory all at once, so an economist, a physician and a demographer can all work from the same data. Questions about aging cross those lines, and the study was designed to cross them too.
“The Health and Retirement Study was the first federal study that combined information about health with really detailed information about finances,” Faul said. “It’s the breadth of the study that’s its true crown jewel.”
What genetics can’t explain
The study, which began in 1990 under economist Tom Juster, has broadened in scope under the leadership team of Langa and Faul. Langa deepened how the study measures memory and thinking. Faul, who co-directs the ISR biospecimen lab, added genetics and blood-based markers of biological aging. And the combination produced a finding that surprised even her.
“Genetics only explains up to 10% of someone’s risk of getting most diseases,” Faul said. “Most of what is important are the decisions people make in their lives, whether they eat well and exercise. Those social and behavioral components have vastly more influence on someone’s healthy life span than genetics does. That was a surprise to me.”
That is the payoff of keeping a person’s biology and biography in the same file. It is also what makes the study hard to run, because someone has to knock on 20,000 doors and keep knocking for decades, in cities and rural counties across all 48 contiguous states, so the sample reflects the country rather than the people most willing to answer a survey.
Why U-M is the perfect place do this work
That kind of fieldwork is where the director of ISR argues U-M is genuinely different. The institute helped invent the science of the representative sample, and it built the standing infrastructure to keep doing it at scale.
“People come to us if they want to engage in conversation with individuals, collect blood work,” said Kate Cagney, who directs ISR.
“ISR is singular in being able to provide that form of infrastructure,” Cagney said, describing it as the choice of social scientists “locally and globally, and across disciplines.”
A model the world now copies
The methodologies behind the Health and Retirement Study have spread well past Ann Arbor. More than 40 countries now run sister studies built on the U-M model, and Langa was careful to frame the network as a two-way exchange. Its value, he said, is not that other countries learn to play by U-M’s rules, but that comparing very different places shows what actually shapes how a population ages, from how long people stay in school to how aggressively doctors treat high blood pressure. Those lessons then feed back into U-M’s own work on aging in the United States.
The data have trained people as well as informed policy. By Langa’s count, about 1,000 doctoral dissertations have been built on the study. Keeping it alive across 34 years and multiple directors means handing it down, and Cagney described that as the generational transmission of skill, pairing young investigators with the people who built the methods. The next generation has to solve problems the founders never faced, from falling survey response rates to the challenges and opportunities associated with artificial intelligence.
The scientists are aging too
The scientists who study aging are aging, too. This is Faul’s 24th year on the study, and next year she reaches the age at which the study would enroll her.
“I’ve gone from talking about older adults my entire career to feeling a little sheepish about saying I research older adults, because I don’t feel old,” Faul said. She has recommitted to walking and to keeping people close, the same habits the data keep rewarding.
For Langa, the pull is personal in a different way. He came to the study in the late 1990s, just as his grandfather was declining with dementia, and he later watched his wife’s grandparents face the same challenges.
“All of the work we’ve done to try to understand how to prevent dementia feels very personal,” Langa said, “It’s such a common condition, and it affects so many people.”
The renewal runs through 2029, and it gives the study more time on questions that still lack solid answers: how families will carry the cost of dementia, how low-income older adults will manage disability, how a graying nation will pay for any of it. Cagney did not hedge about where that work belongs.
“I can’t come up with another place that could respond to all of the unique needs this study has,” said Cagney, adding that ISR is “uniquely situated to respond to our most pressing societal questions.”
Back in his office, Langa will keep making the calls, one participant at a time, to people who have given the study a good part of their lives. That is the trade at the center of it. They keep answering, and the study keeps listening, so the country can know what growing old in America actually looks like.