In terms of biological aging, the body appears to switch three times during our lifespan, research from 2019 suggests – with 34 years, 60 years and 78 years as the major thresholds.
In other words, there is some evidence that aging is not one long, continuous process moving at the same speed throughout our lives.
The findings could help us understand more about how our bodies begin to break down as we age, and how to better address specific age-related illnesses – including Alzheimer’s disease or cardiovascular disease.
The same study has also put forward a new way to reliably predict people’s age using the levels of protein (the proteome) in their blood.
“By deep mining the aging plasma proteome, we identified undulating changes during the human lifespan,” the researchers wrote in their paper, published in December 2019.
“These changes resulted from clusters of proteins moving in different patterns, culminating in three aging waves.”
The team analyzed data from the blood plasma of 4,263 people ages 18 to 95, looked at the levels of about 3,000 different proteins moving through these biological systems, and acted as a snapshot of what is happening in the body: 1,379 of these were found to vary the age.
While these protein levels often remain relatively constant, the researchers found that there were large shifts in the measurements of multiple proteins around young adulthood (34 years), late middle age (60 years), and old age (78 years).
Why and how this happens is not yet clear; but if the proteins can be traced back to their sources, a doctor may, for example, warn you that your liver is aging faster than the average person’s.
It also highlights the link between aging and the blood, something noted in previous studies.
“We’ve long known that measuring certain proteins in the blood can give you information about a person’s health – lipoproteins for cardiovascular health, for example,” said neurologist Tony Wyss-Coray of the Stanford Alzheimer’s Disease Research Center (ADRC) at the time.
“But it is not recognized that the levels of so many different proteins – about a third of all the proteins we have viewed – change significantly as we age.”
The researchers were able to set up a system in which the mix of 373 selected proteins in the blood could be used to accurately predict someone’s age within about three years.
Interestingly, when the system failed to predict an age that was too young, the subject was usually very healthy for his age.
Another finding from the study provides more evidence for something long suspected: Men and women age differently. Of the 1,379 proteins that were found to change with age, 895 (nearly two-thirds) were significantly more predictive of one gender than the other.
These are early findings – the researchers say any clinical applications could take another five to 10 years – and it will take a lot more work to find out how all of these proteins are markers of aging and whether they actually contribute. to it.
Still, it increases the possibility that one day you’ll get a blood test that could measure how well you’re aging, at least on a cellular level.
And the more we know about aging, the more we can do to combat it. That could inform everything from knowing what to drink and eat to potentially add a few years of life, to identifying treatments to prevent some of the worst age-related conditions.
“Ideally, you’d like to know how pretty much everything you’ve taken or done affects your physiological age,” said Wyss-Coray.
The research is published in Nature Medicine
A version of this article was first published in December 2019.