In the study, published today in the Proceedings of the National Academy of Sciences (PNAS), the researchers identify 18 biological measures that could be combined to determine whether people are ageing faster or slower than their peers.
Research tends to focus on ageing in older adults but these findings could help prevent age-related disease by studying ageing much earlier.
The data comes from the Dunedin Study, a landmark longitudinal study that has tracked more than a thousand people born in 1972-73 in the same town from birth to the present day. Health measures like blood pressure and liver function are taken regularly, along with interviews and other assessments.
As part of their regular assessment of this sample at the age of 38 in 2011, the research team measured the function of kidneys, liver, lungs, metabolic and immune systems. They also analysed dental health, cholesterol, cardiorespiratory fitness, lung function and the length of the telomeres – protective caps at the end of chromosomes that have been found to shorten with age.
Based on these biomarkers, the research team set a ‘biological age’ for each participant, which ranged from under 30 to nearly 60 in the 38-year-olds.
They then went back into the archival data for each subject and looked at 18 biomarkers that were measured when the participants were aged 26, and again when they were 32 and 38. From this, they drew a slope for each variable and the 18 slopes were added for each study subject to determine that individual’s pace of ageing.
Most participants clustered around an ageing rate of one year per year, but others were found to be ageing as fast as three years per chronological year. Many were ageing at zero years per year, in effect staying younger than their age.
As anticipated, those who were biologically older at age 38 also appeared to have been ageing at a faster pace. A biological age of 40, for example, meant that person was ageing at a rate of 1.2 years per year over the 12 years the study examined.
Study members who appeared to be more advanced in biological ageing also scored worse on tests typically given to people over 60, including tests of balance and coordination and solving unfamiliar problems. The biologically older individuals also reported having more difficulties with physical functioning than their peers, such as walking up stairs.
Professor Terrie Moffitt from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London and Duke University, said: ‘Eventually if we really want to slow the process of ageing to prevent the onset of disease we’re going to have to intervene with young people.
‘These findings give us some hope that medicine might be able to slow ageing and give people more healthy active years.’
Dr Andrea Danese, also from the IoPPN, said: ‘We are now at a point where we can quantify biological ageing in young people.
‘And for the first time we can see how fast they are ageing. The people who had the oldest biological age were growing old the fastest. If we know that we can think about changing diets or making lifestyle changes when it is early enough to do something about it.
‘With these tests we could detect premature ageing before young people begin to develop heart disease, diabetes or dementia so we could treat them.’
This research was funded by the New Zealand Health Research Council, U.S. National Institute on Ageing, the Medical Research Council (MRC) in the UK, Jacobs Foundation and the Yad Hanadiv Rothschild Foundation.
Notes to editors
‘Quantification of biological ageing in adults’ Belsky D. W. et al. (2015) Proceedings of the National Academy of Sciences
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