How Quickly Are You Growing Old?
Measuring the pace of biological aging in young people could someday help prevent age-related diseases
By Sumathi Reddy
July 13, 2015 1:22 p.m. ET
Feel like you’re 40 years old going on 60? Or maybe, 40 going on 21?
Age may be just a number, but medical experts increasingly are saying it might not always be the right number to gauge your health.
Everybody grows older at a different pace, according to a recent study that found the processes of aging can begin fairly early in life. The study calculated the aging rate of 954 men and women—taking various measurements of their bodies’ health—when they were each 26, 32 and 38 in chronological years. By analyzing how these measures changed over time, the researchers were able to see who aged faster and who slower than normal.
The aim of the research is to be able eventually to identify signs of premature aging before it becomes evident years or decades later in chronic diseases such as cardiovascular disease, diabetes or kidney and lung impairment. “Intervention to reverse or delay the march toward age-related diseases must be scheduled while people are still young,” according to the study, published online last week in the Proceedings of the National Academy of Sciences.
Also, being able to measure aging in young people could allow scientists to test the effectiveness of antiaging therapies, such as calorie-restrictive diets, the study said.
Most of the study participants aged one biological year for each chronological year. Some, however, put on as much as three biological years for every one year, while others didn’t increase in biological age at all during the 12-year span the study surveyed. Using a subset of the biomarkers, the researchers calculated that at 38 years old, the participants’ biological ages ranged from 28 to 61.
Dr. Daniel Belsky, an assistant professor of medicine at Duke University School of Medicine, was first author on a new study that measured the pace of biological aging in young people. Photo: Laura Louison
Studies looking at biological age have been done before, but mainly in older people who already had age-related diseases. Earlier studies also generally took just a single reading that compared chronological with biological age and didn’t examine the pace of aging over time.
“This makes detecting the mechanism of aging difficult because it can be hard to separate aging from a disease-specific mechanism,” said Daniel Belsky, first author of the new study and an assistant professor of medicine at Duke University School of Medicine. “It also may be the case that it’s too late to intervene effectively with some of these individuals” after the age of 40 or 50, he said.
The study by Dr. Belsky and colleagues made use of an unusual cohort: a group of young people, all born in 1972 or 1973, and each of whose biomarkers had been recorded over an extended period. The researchers found data on such a group in a study being conducted in Dunedin, New Zealand, in which an international team of scientists is tracking a range of health measures and behaviors from birth to death.
The research team needed to come up with a set of biomarkers they felt would accurately reflect the aging process. Popular biological-age calculators have proliferated, and websites allow people to enter a few numbers and get a reading. But aging experts say there isn’t as yet a standardized clinical measure of biological age.
The set of 18 biomarkers the team settled on tracked the function of organs such as the liver and kidneys, the immune and metabolism systems and dental health, among other measures.
The results were checked against other tests typically given to elderly people to gauge aging,
including functions such as balance, coordination, grip strength and cognitive abilities.
Participants who showed accelerated aging in the biomarker tests also performed worse on the other tests.
Dr. Belsky hopes the biomarker formulas the team used will ultimately be useful in a clinical setting in a few years. But the measures will need to be refined in future studies looking at different populations, he said. Biomarkers may be dropped or added and given different weights or importance.
“Now there’s work to do to make these measurements better, faster and leaner,” Dr. Belsky said, noting that many of these measures are already taken during regular doctors’ visits.
Nir Barzilai, director of the Institute for Aging Research at Albert Einstein College of Medicine in New York City, said coming up with the right combination of biomarkers to evaluate aging is very important as experts push to develop interventions and therapeutics to target aging and the onset of chronic diseases.
Such tests could result in big medical savings, too, said Dr. Barzilai, who wasn’t involved in the study. “If you’re 60 and you do a test that determines you’re biologically 50, maybe you don’t need a colonoscopy or mammogram every year,” he said.
Dr. Barzilai heads a group of the country’s leading aging experts who are launching a clinical trial to test the diabetes drug metformin to see if it can delay or prevent other chronic diseases often associated with aging. The group hopes to persuade the Food and Drug Administration to consider aging an indication, or preventable condition. Such a move could spur drug manufacturers to target factors that contribute to aging.
Dr. Belsky said the research team also hopes to investigate differences in how fast people age by looking at genetics, lifelong environmental factors and lifestyle behaviors. Previous research on twins has suggested that about 20% of aging can be attributed to genes, so there are many other factors that can be modified to affect the aging process, he said.
Measuring the pace of aging in young people could prove useful to study lifestyle interventions, such as diet and exercise, but are less likely to prompt drug interventions, said James Kirkland, director of the Robert and Arlene Kogod Center on Aging at Mayo Clinic, in Rochester, Minn.
“If you wanted to give a drug to a 38-year-old in an effort to slow or delay or prevent subsequent development of age-related chronic diseases 20 or 30 years later, you would have to have a drug with zero side effects over that amount of time and you would have to prove that,” Dr. Kirkland said.
Stephen Kritchevsky studies functional assessments in older people such as grip and gait, both of which are measures used to determine how well people are aging. Dr. Kritchevsky, who is a professor and director of the Sticht Center on Aging at Wake Forest Baptist Medical Center in Winston-Salem, N.C., said strength typically peaks around age 35 to 40 after which people start losing 1% of their strength per year. That rate accelerates in the 70s and 80s.
How fast older people walk is considered one of the most useful markers for determining future health, Dr. Kritchevsky said. Exercise can help people walk faster, and strength can be improved through resistance training. Balance-training regimens are readily available, including on the National Institute on Aging website. Yoga and tai chi are also believed to help improve balance, he said.
“The primary message is that what happens to us at the end of life has its roots early in life,” said Dr. Kritchevsky of the new study in the Proceedings of the National Academy of Sciences. “Investments in your health in middle age will have payoffs in old age.”
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