Imagine a tool to measure how fast you’re aging… while you’re still reasonably healthy. From a single MRI of your head, researchers can measure your aging rate and predict your risk of dementia and disability years into the future, while you might still have a shot at improving your health. Credit: Ethan Whitman, Duke University
Researchers have created a new
tool that reads how fast you’re aging, using just one brain scan.
The scan can spot signs of future diseases like dementia before
symptoms appear. People aging faster had weaker memory, more health problems,
and even a higher risk of early death. The tool works across different
countries and backgrounds, which makes it even more promising. Scientists hope
it can help find early warning signs and test new treatments before it’s too
late.
Unlocking Why We Age Differently
Ever notice how some people seem to stay sharp and
active as they get older, while others begin to slow down much earlier than
expected? Aging doesn’t happen the same way for everyone.
“The way we age as we get older is quite distinct from
how many times we’ve traveled around the sun,” said Ahmad Hariri, professor of
psychology and neuroscience at Duke University.
Now, scientists from Duke, Harvard,
and the University
of Otago in New Zealand have created a powerful new tool that
shows how fast someone is really aging. And all it takes is one snapshot of the
brain.
Brain Scan Becomes Aging Crystal Ball
With a single MRI scan, the tool can estimate a
person’s risk for developing chronic diseases later in life, long before any
symptoms appear. This early insight could help people make changes to their
lifestyle and diet to stay healthier, longer.
For older adults, the scan can even predict who is
likely to develop dementia and other age-related illnesses. The earlier these
risks are identified, the better the chances of slowing or managing them.
“What’s really cool about this is that we’ve captured how
fast people are aging using data collected in midlife,” Hariri said. “And it’s
helping us predict diagnosis of dementia among people who are much older.”
The results were published today (July 1) in the
journal Nature Aging.
Rethinking Aging Clocks
Finding ways to
slow age-related decline is key to helping people live healthier, longer lives.
But first “we need to figure out how we can monitor aging in an accurate way,”
Hariri said.
Several algorithms have been developed to measure how
well a person is aging. But most of these “aging clocks” rely on data collected
from people of different ages at a single point in time, rather than following
the same individuals as they grow older, Hariri said.
Life-long Study Fuels New Metric
“Things that look like faster aging may simply be
because of differences in exposure” to things such as leaded gasoline or
cigarette smoke that are specific to their generation, Hariri said.
The challenge, he added, is to come up with a measure
of how fast the process is unfolding that isn’t confounded by environmental or
historical factors unrelated to aging.
To do that, the researchers drew on data gathered from
some 1,037 people who have been studied since birth as part of the Dunedin
Study, named after the New Zealand city where they were born between 1972 and
1973.
From Health Markers to PACNI Score
Every few years, Dunedin Study researchers looked for
changes in the participants’ blood pressure, body mass index, glucose and
cholesterol levels, lung and kidney function and other measures – even gum
recession and tooth decay.
They used the overall pattern of change across these
health markers over nearly 20 years to generate a score for how fast each
person was aging.
The new tool, named DunedinPACNI, was trained to
estimate this rate of aging score using only information from a single brain
MRI scan that was collected from 860 Dunedin Study participants when they were
45 years old.
Next the researchers used it to analyze brain scans in
other datasets from people in the U.K., the U.S., Canada and Latin America.
Faster Aging and Higher Dementia Risk
Across data
sets, they found that people who were aging faster by this measure performed
worse on cognitive tests and showed faster shrinkage in the hippocampus, a
brain region crucial for memory.
More soberingly, they were also more likely to
experience cognitive decline in later years.
In one analysis, the researchers examined brain scans
from 624 individuals ranging in age from 52 to 89 from a North American study
of risk for Alzheimer’s disease.
Those who the tool deemed to be aging the fastest when
they joined the study were 60% more likely to develop dementia in the years
that followed. They also started to have memory and thinking problems sooner
than those who were aging slower.
When the team first saw the results, “our jaws just
dropped to the floor,” Hariri said.
Body-Brain Aging Connection
The researchers also found that people whose
DunedinPACNI scores indicated they were aging faster were more likely to suffer
declining health overall, not just in their brain function.
People with faster aging scores were more frail and
more likely to experience age-related health problems such as heart attacks,
lung disease or strokes.
The fastest agers were 18% more likely to be diagnosed
with a chronic disease within the next several years compared with people with
average aging rates.
Universal Patterns, Stark Outcomes
Even more alarming, they were also 40% more likely to
die within that timeframe than those who were aging more slowly, the
researchers found.
“The link between the aging of the brain and body is
pretty compelling,” Hariri said.
The correlations
between aging speed and dementia were just as strong in other demographic and
socioeconomic groups than the ones the model was trained on, including a sample
of people from Latin America, as well as United Kingdom participants who were
low-income or non-White.
“It seems to be capturing something that is reflected in all brains,” Hariri said.
Longevity’s Looming Health Costs
The work is important because people worldwide are living
longer. In the coming decades, the number of people over age 65 is expected
to double, reaching nearly one
fourth of the world’s population by 2050.
“But because we live longer lives, more people are
unfortunately going to experience chronic age-related diseases, including
dementia,” Hariri said.
Dementia’s economic burden is already huge. Research
suggests that the global cost of
Alzheimer’s care, for example, will grow from $1.33 trillion in 2020
to $9.12 trillion in 2050, comparable or greater than the costs of
diseases like lung disease or diabetes that affect more people.
Effective treatments for Alzheimer’s have proven
elusive. Most approved drugs can help manage symptoms but fail to
stop or reverse the disease.
Catching Alzheimer’s Before It Strikes
One possible explanation for why drugs haven’t worked
so far is that they were started too late, when the Alzheimer’s proteins that
build up in and around nerve cells have already done too much damage.
“Drugs can’t resurrect a dying brain,” Hariri said.
But in the future, the new tool could make it possible
to identify people who may be on the way to Alzheimer’s sooner, and evaluate
interventions to stop it – before brain damage becomes extensive, and without
waiting decades for follow-up.
Future of Personalized Aging Risk
In addition to
predicting our risk of dementia over time, the new clock will also help
scientists better understand why people with certain risk factors, such as poor
sleep or mental health conditions, age differently, said first author Ethan
Whitman, who is working toward a Ph.D. in clinical psychology with Hariri and
study co-authors Terrie Moffitt and Avshalom Caspi, also professors of
psychology and neuroscience at Duke.
More research is needed to advance DunedinPACNI from a research tool to something that has practical applications in healthcare, Whitman added.
But in the meantime, the team hopes the tool will help
researchers with access to brain MRI data measure aging rates in ways that
aging clocks based on other biomarkers, such as blood tests, can’t.
“We really think of it as hopefully being a key new
tool in forecasting and predicting risk for diseases, especially Alzheimer’s
and related dementias, and also perhaps gaining a better foothold on the
progression of disease,” Hariri said.
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