New research suggests that in terms of biological aging the body appears to shift gears three times in our lifetime. The key thresholds are 34 years, 60 years and 78 years.
In other words, we now have evidence that biological aging is not a long, continuous process that moves at the same speed throughout life.
The findings could help us understand more about how our bodies begin to "break down" as we age and how specific age-related diseases (including Alzheimer's and cardiovascular disease) could be better addressed.
The same study also proposed a new way to reliably predict people's ages using the levels of protein (the proteome) in their blood.
In the published paper, the researchers describe the identification of a "wavy" nature of changes in protein levels throughout life.
"These changes were the result of clusters of proteins moving in distinct patterns, culminating in the emergence of three waves of aging."
The team analyzed data from the blood plasma of 4.263 people aged 18 to 95, looking at the levels of about 3.000 different proteins moving through these biological systems and acting as a snapshot of what is happening in the body: of these, 1.379 were found to vary with age.
While these protein levels often remain relatively constant, the researchers found that large changes occurred in the readings of multiple proteins. Around young adulthood (34 years), advanced middle age (60 years) and old age (78 years).
Why does it happen?
It is not yet clear why, nor how: but analyzing in detail the sources of each protein will allow us to understand how much and at what speed each single organ in our body ages.
The research also highlights the important link between biological aging and blood, something that has been identified in previous studies.
"We have known for a long time that measuring certain proteins in the blood can give you information about a person's health status, for example lipoproteins for cardiovascular health". The neurologist says so Tony Wyss-Coray, of the Stanford Alzheimer's Disease Research Center (ADRC). "But it has never been discovered before that the levels of so many different proteins (about a third of those observed) change markedly with advancing age."
Tell me what protein you have, and I'll tell you how old you are
The researchers were able to establish a system whereby the blend of 373 selected proteins in the blood could be used to accurately predict someone's age. And with a margin of error of only a year and a half more or less.
Men and women, different biological aging
We know, men live less. But another study result provides further evidence for this ancestral reality. 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 for one sex than the other.
At least 5 years for a revolution
These are still early results. Researchers say any clinical application is still 5-10 years away). It will take a lot of work to understand how all these proteins are markers of biological aging and if they actually contribute to it.
When the studies are completed, however, one day we will have a blood test that can also measure how much and how we are getting older.
And the more we know about the mechanisms of aging, the more we can fight it with proper care.
Such an examination can translate into our personal maintenance booklet. From knowing what to drink, what to eat, what to add to our diet, to new treatments to avoid age-related ailments.