It’s the kind of thing that gets hard to ignore at class reunions. And in fact, it was a reunion – of sorts.
In 2019, Avshalom Caspi and Terrie Moffitt, both psychology professors at Duke, were interviewing participants in a landmark long-term study in New Zealand. The husband-and-wife research team have been following the lives of the same 1,000 people for decades, tracking their mental and physical health as part of the Dunedin Study, named after the New Zealand city where the study participants were born between April 1, 1972, and March 31, 1973.
Now, as the participants entered midlife – their late 40s – it was becoming clear that some were aging earlier and faster than others. One person might spring up from their chair and stride across the room with ease. Another might moan and groan with every movement, says Caspi, Edward M. Arnett Professor of Psychology & Neuroscience.
On tests of balance and mobility, memory and concentration, it was the same story. Despite having the same age on their driver’s licenses, “they were wildly different from each other,” Moffitt says.
If they could figure out what was driving the differences, the researchers reasoned, perhaps they could use that information to slow the aging process. But first they needed a way to measure it.
So in 2020 they developed an algorithm, now licensed to the company TruDiagnostic, that measures how fast you’re aging. “It’s a lot like a speedometer,” says Moffitt, Nannerl O. Keohane University Professor of Psychology.
To build the tool, every few years Dunedin Study researchers and their colleagues at the University of Otago in New Zealand tracked changes to the participants’ blood pressure, lung capacity, glucose and cholesterol levels, mental processing and other measures – even gum disease and tooth decay.
“Aging isn’t just your heart breaking down or your kidneys falling apart,” Caspi says. “It’s the gradual synchronized decline of multiple different organs over time.”
They used the overall pattern of change across these health markers over two decades to build a model that is able to tell, from a single blood test, whether you’re aging faster than expected and predict your risk of disease and disability years into the future – while you might still have a shot at improving your health.
The researchers took the test themselves last fall. Caspi was aging slightly faster than expected – more than 12 months for every calendar year. “Which was slightly demoralizing,” he confessed. “I would like to think of myself as a fairly robust person.”
Moffitt’s test results suggested she was aging slightly slower than most people her age. For every 12 months, she was aging only 11.5. “Over 20 years, it would add up to a whole year slower,” she says.
If, say, you’re 50 now, the prospect of turning 70 but still having the mind and body of a 69-year-old might not mean much.
But for the researchers, the test is more than a way to measure aging rate. It’s a way to figure out whether interventions can slow it down.
The measure, called DunedinPACE, has been used in more than 400 scientific publications so far. More recently, they developed a similar aging clock that relies on a brain scan instead of a blood sample. Called DunedinPACNI, the test can predict a person’s risk of developing dementia years before symptoms emerge.
The DunedinPACE test is available to consumers at TruDiagnostic.com. The brain scan test is available for researchers but not yet for consumers. But “it’s not necessary to get tested to take action,” Moffitt says.
That’s because the keys to healthy aging are no big secret. “We already knew what the fountain of youth was. It’s nothing mystical or magical,” Moffitt says.
Living on the same North Carolina land that Moffitt explored as a kid, a 300-acre tract that was her grandparents’ dairy farm, Moffitt says they both try to eat a healthy diet, stay physically active, nurture meaningful relationships. “We have an enormous vegetable garden, and we go to every church potluck we can,” Moffitt says.
What their research suggests is that whether you are young, middle-aged or older, it’s never too early or too late to make a lifestyle change for the better.
If funding allows, the researchers hope to see the Dunedin Study participants again at their next follow-up at age 59. “Prevention is important,” Moffitt says. “But we’re getting more and more evidence that it’s important to give people second chances, too.”