Wednesday July 8 2015
Your ‘biological age’ may not be the same as your actual age
"Ageing rates vary widely, says study," BBC News reports. For 12 years, researchers tracked a range of biomarkers associated with the ageing process.
Biomarkers are indicators of how well certain biological processes or systems are functioning.
In this study, the researchers described age-related biomarkers as signs of "gradual and progressive deterioration of integrity across multiple organ systems".
The biomarkers used included cholesterol levels, gum health and body mass index, among others.
The idea being that, for example, your chronological age could be 30, but you could have the cholesterol levels of a typical 50-year-old.
Researchers looked at just over 1,000 mainly white adults in New Zealand followed from birth to age 38, and information on the biomarkers was collected from the ages of 26 to 38.
The study found that people who had a higher "biological age" also had a higher "pace of biological ageing". Both were associated with poorer physical and cognitive function, feeling less healthy, and looking older at age 38.
These early stage results will need to be confirmed in larger and broader samples. The idea is that the methods used in the study could eventually be useful in assessing the effectiveness of any future anti-ageing treatments.
The obvious question is: What can people do to slow down their pace of ageing? There is currently no definitive answer to that question. What we do know is regular exercise, a balanced diet and maintaining a healthy weight will give you the best chance of keeping healthy.
Where did the story come from?
The study was carried out by researchers from Duke University and other research centres in the US, UK, Israel and New Zealand. It was funded by the US National Institute on Aging, UK Medical Research Council and the Jacobs Foundation. The New Zealand centre received funding from the New Zealand Health Research Council, and another author received support from the Yad Hanadiv Rothschild Foundation.
The study was published in the peer-reviewed journal Proceedings of the National Academy of Sciences (PNAS) of the USA. The study has been published on an open-access basis, so it is free to read online or download as a PDF.
While the majority of the UK media’s reporting of the study was accurate and informative, the Mail Online decided to go on a flight of fancy with the question: "Has science finally cracked the secret of eternal youth?" The obvious answer being: "No".
What kind of research was this?
This was an analysis of data from a cohort study, which aimed to develop ways to assess "biological ageing" in young adults.
The global population is ageing, and increasing age is linked to more disease and disability. Because of humans’ long life span, much of the research into ageing is done in animals with short lifespans, or in older adults, many of whom already have age-related illnesses. The researchers say that one of the reasons why younger people are not studied is that assessing biological ageing in this age group is controversial, as there are various possible indicators, and findings have been mixed. They wanted to see if they could develop reliable ways to do this.
If there were such measurement tools, researchers would like to use these to give an early indication of whether any new "anti-ageing" treatments might be working. This would be quicker than having to wait until people develop age-related diseases or to see how long they live.
This is an appropriate approach to developing these measures, but ideally the research would continue to follow up people, to see if their measures correctly predict health in later life, or their lifespan.
What did the research involve?
The researchers studied 1,037 adults from Dunedin in New Zealand, who had been followed up from birth to age 38. They assessed a range of biological characteristics tested at age 26, 32 and 38, to see if some people seemed "biologically older" than others of the same age, and whether people aged at different rates.
The researchers first looked at biological age, using what was known as the "Klemera-Doubal method", which had been shown to be a better predictor of risk of death than a person’s age alone in a previous US study. This method assesses 10 biological characteristics, including tests of lung function, blood pressure and cholesterol, among others.
They used the Klemera-Doubal method to assess biological age in their study participants at age 38. They then looked at 18 different biological characteristics measured in participants at ages 26, 32 and 38, to see how much they had changed. The characteristics assessed are ones which change with age. They included assessments of the heart and blood (cardiovascular), metabolic and immune systems, as well as the kidneys, liver, gums, lungs and DNA. Some of these characteristics were also included in the biological age calculation.
They used this information to calculate each person’s "pace of ageing" compared to the average change over one year within the group. They then compared whether those with an older Klemera-Doubal biological age showed a more rapid "pace of ageing" than those with a younger biological age.
Finally, they compared physical and cognitive function, and self-rated health among those with different biological ages or pace of ageing. They also got blinded raters to guess how old individuals were from a photo, to see if this differed among those with different biological ages or pace of ageing.
What were the basic results?
The researchers found that, according to the Klemera-Doubal method, their sample of 38-year-olds had biological ages ranging from 28 to 61.
The 18 biological characteristics they followed showed different rates of change in different people from the ages of 26 to 38. They calculated people’s "pace of ageing" based on these characteristics, and found that some people showed zero years of biological change per chronological year, while others showed almost three years of biological change per chronological year.
People with an older biological age had a more rapid pace of ageing from the ages of 26 to 38 than those with a younger biological age. Each year increase in biological age compared to actual age added a 0.05 year increase in pace of ageing. So, a person who was 38 but had a biological age of 40 was estimated to have aged 1.2 years faster over the past 12 years, compared to a person who had a biological age of 38.
They also found that at age 38, those with a higher biological age or faster pace of ageing performed less well on physical and cognitive function tests than those with a younger biological age or slower pace of ageing. Those with a higher biological age or faster pace of ageing had also rated themselves as less healthy and were estimated to be older based on facial appearance by volunteers who did not know the participants’ ages.
How did the researchers interpret the results?
The researchers concluded that, "young individuals of the same chronological age varied in their 'biological ageing'" and that "already, before midlife, individuals who were ageing more rapidly were less physically able, showed cognitive decline and brain ageing, self-reported worse health, and looked older". They suggest that these measures of biological ageing in young adults could be used to identify causes of ageing and evaluate anti-ageing treatments.
This study has developed a new method of assessing the "pace of biological ageing" over time in adults under 40. It showed an association between this measure and another measure of biological age, as well as physical and cognitive function, and how healthy people felt and how young they looked.
In some ways, these results are unsurprising, as the biological measures assessed are measures relating to health, such as blood pressure and cholesterol, as well as measures of fitness and weight.
These results will also need to be confirmed in larger and broader samples – for example, of different ethnicities – as the study was in mainly white participants. Longer-term studies would also be needed to assess whether these measures predict health outcomes at later ages, or lifespan.
As for practical implications, this sort of measure is most likely to be used in research. It’s unlikely that individuals will be able to use this method to calculate their biological age, as the measures used need blood and other clinical tests, and getting the "pace of ageing" needs measurements collected over 12 years. We also don’t yet know whether interventions, either lifestyle or drug treatments, will impact this "biological ageing".
Based on what we already know, to maximise your chances of living a long and healthy life, taking steps such as maintaining a healthy weight, eating a varied and balanced diet, keeping physically active, moderating your consumption of alcohol and avoiding smoking are likely to be your best bet.