At a school or college reunion, say a 20th one, have you wondered how some of your batchmates look much younger or older than you, despite all of you being born most probably in the same year? Are you ageing differently? Indeed you are, say the leaders of a large long-term human health study in New Zealand that has sought clues to the ageing process in young adults.
In a paper in the Proceedings of the National Academy of Sciences, the team introduces a panel of 18 biological measures that may be combined to determine whether people are ageing faster or slower than their peers. The data comes from the Dunedin Study, a landmark study that has tracked more than a thousand people born in 1972-73 in the same town from birth to the present.
Starting early
“We set out to measure ageing in these relatively young people,” says first author Dan Belsky, an assistant professor of geriatrics in Duke University’s Center for Ageing. “Most studies of ageing look at seniors, but if we want to be able to prevent age-related disease, we’re going to have to start studying ageing in youngsters.” Belsky says the progress of ageing shows in human organs just as it does in eyes, joints, and hair, but sooner.
So as part of their regular reassessment of the study population at age 38 in 2011, the team measured the functions of kidneys, liver, lungs, metabolic and immune systems. They also measured HDL 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.
Biological age
The research team set a “biological age” for each participant, which ranged from under 30 to nearly 60 in the 38-year-olds. The researchers then went back into the archival data for each subject and looked at 18 biomarkers that were measured when the participants were age 26, and again at 32 and 38. From this, they drew a slope for each variable, and then 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 the team expected, 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 aging at a rate of 1.2 years per year over the 12 years the study examined. The ageing process isn’t all genetic. Studies of twins have found that only about 20 per cent of ageing can be attributed to genes, Belsky says. “There’s a great deal of environmental
influence.”
“That gives us some hope that medicine might be able to slow ageing and give people more healthy active years,” says senior author Terrie Moffitt, professor of psychology and neuroscience at Duke.
— Source: www.futurity.org
