If someone asks you, “how old are you?”, you automatically calculate the answer from the day you were born. But scientists have discovered that in addition to our chronological age, it is possible to measure another type related to the health level of your organs: biological age.
To reveal it, scientists have been developing for years tools called “aging clocks”, capable of assessing the state of the organs of the human body and estimating how many healthy years are left for that person.
However, it seems that making this calculation is not as simple as it seems. Therefore, the accuracy of each tool tested has varied greatly. Meet the aging watches we know today.
Watches powered by blood and inflammation
The DNAm PhenoAge biological clock emerged in 2018. Steve Horvath, Morgan Levine and other scientists created it with data collected from thousands of people in the United States after years of study.
According to this clock, if your age is older than chronological, you would be aging faster than average. For example, one year older than you are chronologically would represent a 9% increase in death, as well as an increase in the possibility of having cancer, diabetes, or heart disease.
Another type of watch, also developed by Horvath, was the GrimAge. The scientist used the watch on his own blood samples, obtaining the result of a biological age compatible with the chronological one, two years ago. But six months ago, the test was redone and now Horvath’s biological age is four years older than his chronological age. That doesn’t mean he “lost” four years of his life, but he believes he’s aging faster than he should.
There is also iAge, from Edifice Health, which provides age based on the body’s immune health and inflammatory levels, using reference values for each age. This type of “biological clock” predicts chronic inflammatory diseases, longevity and immunosenescence, that is, age-related deterioration and inadequate immune system functions. The scientists used data from the Stanford 1000 Immunomes Project, which collected blood samples for nine years from 1,001 people ages 8 to 96.
How aging watches are made
As we age, patterns in our DNA known as methyl groups — the name for a substance that combines one carbon atom with three hydrogen atoms — change. The exact reason is not known. Most aging clocks estimate a biological age from these pattern changes.
But that’s not the only way it works: other tools act like a speedometer, keeping up with the pace of aging; or even estimating how one’s body has aged over the years. Some watches were made for certain organs or for various species of animals.
From chronological to biological clocks
The first aging watch was developed in 2011 also by Steve Horvath at the University of California. He offered to participate in a study with his twin brother Markus, trying to understand if there were any indications that would explain the two brothers’ different sexual orientation.
Even though he didn’t find anything to that effect, Steve discovered another fact: that methyl patterns could predict people’s age in years, that is, chronologically, although the estimates reached diverge by about five years.
In 2013, Horvath developed the eponymous Horvath watch, also called a “pantissue” watch and capable of estimating the age of any organ in the body. He did this from 8,000 samples representing 51 types of body tissues and cell types – data that served to train the algorithm and predict someone’s chronological age from a cell sample.
It was an admirable feat, but one that did not impress the scientific community; after all, it only served to prove someone’s chronological age. So in 2018, Horvath teamed up with Morgan Levine and other colleagues to create a clock based on nine biomarkers, such as blood glucose levels and white blood cells, in addition to chronological age itself, to know the biological age of each human body.
This answer would be more interesting because it would help measure the body’s overall health, how many healthy years the person is left, how the organs are responding to the environment, and it gives information for care such as anti-aging medications and changes in habits.
It still lacks precision, but we know habits that get old
Although some use the decrease in biological age years to link to the use of supplements, in many cases these changes can be explained by the clocks being considered error-prone.
In each area of the body where methyl groups attach to DNA, small changes can occur over time and cause errors in estimates. To improve this, scientists are “cracking” existing clocks and comparing them with each other in order to build better equipment.
For now, blood pressure and cholesterol tests serve well as indicators of general health. In addition, exercising, eating well and avoiding drinking and smoking are the most traditional ways to seek a balanced and long life. Recent research from the University of Oxford in the UK found that excessive alcohol consumption accelerates the biological clock and causes premature aging.