You may have wondered why you look older or younger than your agemates.

Well, scientists now argue that such perceptions go beyond outward appearances, exposing the different paces at which individuals age, and the implications on one’s health.

A recent study published in the US journal Proceedings of the National Academy of Science described 18 “biomarkers,” established as risk factors or correlates of chronic disease and mortality, which were tested on a group of 1,037 people, born from 1972-1973 in New Zealand, to show how quickly human beings age.

The individuals were followed from the time they were 26 until they were 38 years of age.

The biomarkers not only proved to be good indicators of one’s physiological age but also reflected the biological effects of ageing common in older people. They were also a good indicator of one’s biological age, meaning that those who aged faster also looked older in appearance.

The biomarkers tested included blood pressure, cholesterol levels, lung function, inflammation, body mass index, metabolic and immune system, kidneys, livers, gums and the integrity of the DNA.

The study is considered critical because human ageing research is still restricted to older adults, many with chronic disease, ignoring the fact that ageing is a gradual process that needs to be studied over a long period of time.

As a result of this anomaly, the study focused on the youthful population because little is known about ageing in young people, even though they are the most attractive targets for therapies to extend healthspan.

“The science of healthspan extension may be focused on the wrong end of the lifespan; rather than only studying old humans, science should also study the young,” said the scientists led by Daniel Belsky, an assistant professor of medicine at the Duke University School of Medicine in the US.

After testing the biomarkers of the participants, the researchers then calculated a biological age for each volunteer, based on the scores each participant got on the measures at age 26. The tests were repeated when the participants were 32 and 38-years-old.

The researchers then combined them to calculate the pace at which each person was ageing.

The study found that some people were biologically older and ageing faster than others, despite being the same chronological age. The researchers also discovered that the ageing changes were the same as those occurring later in life, after administering the same skills tests to participants.

However, the good news is that not all were older than they were; some were younger than their chronological age and ageing more slowly than normal.
Comparing the slower and faster ageing groups is important since it can reveal ways of delaying ageing in life.

According to Nairobi-based consultant physician Daniel Abongo, the research can also help scientists understand better the factors that influence ageing, especially among the youthful population.

“If successful, the research will not only help us better understand the causes of ageing but also how to slow the process using medication and other means,” said Dr Abongo.

Though there has been scepticism about whether the ageing process can be detected in young adults who do not have chronic diseases, the researchers found otherwise. They found that the ageing processes can be quantified in people young enough to prevent age-related diseases.

Once the individual in the study celebrated their 38th birthday, for example, the scientists examined their physiologies to test whether the population would show evidence of individual variation in ageing despite remaining free of age-related disease.

“We further tested whether, by midlife, young adults who were ageing more rapidly already exhibited deficits in their physical functioning, showed signs of early cognitive decline, and looked older to independent observers,” the researchers added.

They found that study members with advanced biological ages had experienced a more rapid pace of ageing over the past 12 years compared with their biologically younger peers.

Each year, an increase in biological age was associated with a 0.05-year increase in the pace of ageing relative to the population norm.

In other words, a 38-year-old with a biological age of 40 years was estimated to have aged 1.2 years faster over the course of the 12-year follow-up period, compared with a peer whose chronological age and biological age was 38.

“This estimate suggests that a substantial component of individual differences in biological age at midlife emerges during adulthood,” the study added.
Study members with advanced biological age did not perform as well on objective tests of physical functioning at age 38 as biologically younger peers.

“They had more difficulty with balance and motor tests (for unipedal stance test of balance; for grooved pegboard test of fine motor co-ordination), and they were not as strong (grip strength test),” the study said.

The study also discovered that accelerated ageing in young adults also influenced indicators of brain ageing. Study members with older biological ages had poorer cognitive functioning at midlife.

Healthy adults who were ageing faster showed evidence of cognitive decline and increased risk for stroke and dementia relative to slower-ageing peers.
They also felt less healthy and were rated as looking older by independent observers.