Aging clocks aim to predict how long you’ll live

Most aging clocks estimate a person’s biological age based on a pattern of epigenetic markers ખાસ in particular, chemical tags called methyl groups that are layered on DNA and affect how genes are expressed. The pattern of this methylation in thousands of sites on DNA seems to change with our age, although it is not clear why.

Some clocks promise to predict life by estimating how old a person’s body is, while others work like a speedometer, which tracks the aging process. Clocks have been developed for specific body parts and for many animal species.

Proponents of her case have been working to make the actual transcript of this statement available online. But we do not yet have enough information about watches or what they tell us to make such claims.

Tracking time

The first epigenetic aging clock was developed in 2011 when Steve Horvath of the University of California, Los Angeles, volunteered to participate in the study with his twin brother, Marcus. The study was looking for epigenetic markers in saliva samples that could explain the sexual orientation. (Steve is straight and Marcus is gay.)

As a biostatician, Horvath offered to analyze the results and found no link with the sexual orientation. But he also found links between the age of the volunteers and the epigenetic markers. He says, “I fell off my chair because the sign of aging was too big.”

He found that patterns of methylation can predict a person’s age over years, although estimates vary by an average of five years from each person’s chronological age.

Since then Horvath has worked on older watches. In 2013, he developed the so-called Horvath watch, one of the oldest known watches today, which he calls a “pan-tissue” watch because it can estimate the age of any body part. Horvath constructed the clock using methylation data from 8,000 samples representing 51 body tissue and cell types. With this data, he trained an algorithm to predict the chronological age of a person from a cell sample.

Other groups have developed similar clocks, and hundreds still exist today. But Horvath estimates that less than 10 are widely used in human studies, primarily to assess how diet, lifestyle, or supplements may affect aging.

Measuring age

What can all these watches tell us? It depends. Most watches are designed to predict chronological age. But Morgan Levine at the Yale School of Medicine in New Haven, Connecticut, says: “For me, that’s not the goal. We can ask someone how old they are. ”

In 2018, Levine, Horvath and colleagues developed a clock based on nine biomarkers, including blood levels of glucose and white blood cells, as well as a person’s age.

They used data collected from thousands of people in the U.S. as part of a separate study that followed participants for years. The resulting clock, called DNAm PhenoAge, is better at estimating biological age than clocks based on chronological age alone, says Levin.

A one-year increase in what Levine calls a “phenotypic” age, clockwise, is associated with a 9% increase in deaths from any cause, as well as an increased risk of dying from cancer, diabetes or heart disease. Levine says that if your biological age is greater than your chronological age, it is reasonable to assume that you are aging faster than average.

But that may not be the case, says Daniel Belsky of the Columbia University Mailman School of Public Health in New York City. He says there are many reasons why a person’s biological age exceeds a year.

Belsky and colleagues have developed a tool to more accurately measure the rate of biological aging, tracking the health outcomes of 954 volunteers between the ages of four between their mid-20s and mid-40s, based on their work. The researchers looked at biomarkers believed to show how well the various organs as well as other organs connected with general health are functioning. They then developed an epigenetic “speedometer” to predict how these values ​​would change over time.

Another popular watch, which was also developed by Horvath and his colleagues, is called Grimm Reaper in a nod to the Grim Reaper. Horvath claims he is the best at predicting mortality, and he is applying it to his own blood samples.

His results were consistent with his chronological age two years ago, he says, but when he took the second test about six months ago, his Grimage was four years older than his age. That doesn’t mean Horvath has taken four years out of his life – “you can’t relate directly to how long you live,” he says – but he thinks it does mean he’s getting older faster. Is happening, although he is still confused as to why.

Noisy clocks

Others have used the change in their results to predict that their aging rate will slow down, usually after they start taking supplements. But in many cases, the change can be explained by the fact that many epigenetic aging clocks are “noisy” – random errors that distort their results.

The problem is that in every area of ​​the body where methyl groups attach to DNA, very minor changes occur over time. These subtle changes can be exacerbated by errors in methylation estimates. Levine says it’s a big problem, and the results could last for decades.

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