Secret of what makes us appear 36 years younger...

Scientists delve into the biology of how people age at vastly different rates

SOME older people are ageing so badly that their body is 48 years older than their actual age, scientists have found.

In contrast, other socalled “super-agers” are growing old surprisingly slowly, and may be biologically still in their 20s.

Researchers at the University of Southern California looked at the rate of change occurring to the DNA of more than 4,000 over-57s and found striking differences between biological age and chronological age.

At the far end of the scale one 66-year-old was found to have a biological age of 114, while another 59-yearold was physically just 23.

The team looked at epigenetic changes, which are modifications to DNA that turn genes “on” or “off”.

With epigenetic changes, the DNA sequence remains unchanged, but cells start to “read” genes differently, like switching programmes on a washing machine, or dimming a light. The changes alter how the body functions and can trigger disease.

Damaging environmental factors such as smoking, stress, pollution or obesity cause the alterations, and the culmination of epigenetic changes can be used like a clock to determine how fast a person is ageing.

Dr Eileen Crimmins, Professor of Gerontology, at the University of Southern California, said: “Some people who are 57 or older look like they’re in their twenties, while some people look like they’re over 100, and there’s a big range in between.

“We think that adverse social experiences can change your epigenetic profile in ways that may subsequently influence your health adversely. There were people who looked 36 years younger, while some look 48 years older.

“People believe that the underlying process of ageing is one that underlies all the different health outcomes linked to age, such as cognitive decline, disease, disability, frailty and mortality.”

Researchers took blood samples from participants and tested them against three “epigenetic clocks” to measure DNA changes at different points of the genetic code.

Their goal was to find out which social factors were speeding up or slowing the ageing process and so they compared the clock results to participants’ education, life traumas, mental health, race and sex to see if they could tease out which events were contributing to ageing.

“We have lots of evidence that these social factors are linked across the board to the major health outcomes associated with age, and we’re attempting to try to understand the biology of how social factors affect ageing outcomes,” added Prof Crimmins.

They found that being female slowed down the ageing clock by up to two years, while obesity speeded it up by up to 18 months. Suffering psychological distress also increased biological age by around four months, and poor childhood health also accelerated ageing.

The research was presented at the AAAS meeting in Seattle. Full findings are due to be published in March.