Why do some of your friends -- who are the same age as you are -- look so much younger than you do? Why do some look so much older?
It seems that people really do age at different rates, and it starts fairly early in life, according to a long-term human health study in New Zealand that has sought clues to the aging process in young adults. In a study published in the Proceedings of the National Academy of Sciences, the team posits 18 biological parameters -- blood pressure and liver function have been taken regularly, along with other assessments -- that can be combined to determine whether people are aging faster or slower than their peers. These guidelines come from the Dunedin Study, which has kept track of more than a thousand people born in 1972-73 in the same town from birth to the present (http://www.futurity.org/aging-young-adults-954962/).
According to first author Dan Belsky, assistant professor of geriatrics in Duke University's Center for Aging, "We set out to measure aging in relatively young people. Most studies of aging look at seniors, but if we want to be able to prevent age-related disease, we're going to have to start studying aging in young people."
Belsky explains that the objective is to be able to intervene in the aging process. The progress of aging is apparent in human organs just as it is in eyes, joints, and hair, so the team measured the functions of kidneys, liver, lungs, metabolic and immune systems, as well as HDL cholesterol, cardiorespiratory fitness, lung function and the length of the telomeres, the caps at the end of chromosomes that shorten with age. Additionally, they measured dental health and the condition of the tiny blood vessels at the back of the eyes.
Using these biomarkers, the researchers determined a "biological age" for each participant, which ranged from under 30 to nearly 60 in the 38-year-olds. They then looked at 18 biomarkers that were measured when the participants were 26, 32 and 38. From these data, they determined each individual's pace of aging.
Most of the participants aged at the rate of one year per chronological year, while others aged three times as fast. Many aged at zero years per year, which means that they were effect staying younger than their chronological age in functional terms. While most people see the aging process as something that happens late in life, but signs of aging were already apparent in these tests in the course of 12 years of young adulthood: from 26 to 38, Belsky says. The ultimate goal is to be able to intervene in the aging process itself.
The Dunedin study in New Zealand, which tracked more than 1,000 people born in the South Island city of Dunedin in 1972-1973 from birth to the present, aims to develop a new method to determine biological aging that could be "a breakthrough in therapies that slow aging and help prevent age- related diseases before they occur," said researchers at the University of Otago. Otago University Professor Richie Poulton says that when the 18 measures were assessed together in study members at age 38, they were able to set "biological ages" for each person. People aging more rapidly were less physically able, showed cognitive decline and brain aging, reported worse health and looked older. The ability to detect accelerated aging at an early stage paved the way for applying therapies that slowed aging and lessen age- related ailments (http://news.xinhuanet.com/english/2015-07/07/c_134389283.htm).
"By 2050, the world population aged 80 years and over will approach 400 million people, so we are facing an enormous global burden of disease and disability unless we can extend healthy lifespans," Poulson concludes.