Hundreds of dollars spent, but how reliable are 'biological age' tests?

Biological age tests cost hundreds of dollars but face scrutiny

Sleep, meal timing can skew results, experts warn

Experts: don't fixate on numbers; standard checkups more useful

Questions are growing about the reliability of "biological age tests" — screenings that cost hundreds of dollars and claim to measure how old a person's body really is. While the tests have gained popularity for their promise of revealing the true pace of aging beyond chronological age, experts say results can shift depending on everyday lifestyle habits and that the tests still fall short of accurately predicting individual health outcomes.

According to The New York Times on Thursday (local time), experts say biological age tests show promise as tools in longevity and aging research but need significant improvement before ordinary consumers can rely on them for health management.

Unlike chronological age — the number of years since birth — biological age reflects how much the body has actually aged. Two people who are both 50, for example, may be in very different physical shape: one person's body could resemble that of an average person in their 40s, while the other's could be aging closer to someone in their 60s.

"If your biological age is higher than your chronological age, you are at greater risk of negative health outcomes," said Luigi Ferrucci, scientific director at the US National Institute on Aging. "Conversely, if your biological age is lower than your chronological age, you can consider yourself somewhat protected from those health risks."

The most widely known biological age tests analyze chemical changes in DNA, with a process called DNA methylation at the center of the approach. DNA methylation refers to chemical modifications that influence whether certain genes are activated. Researchers discovered that these modifications follow consistent patterns as people age, which led to their use in aging-measurement technology.

Despite advances in biological age testing technology, questions about its accuracy and reliability when applied to individuals remain.

Albert Higgins-Chen, an assistant professor of psychiatry and pathology at Yale School of Medicine, said "the time of day you get tested, when you last ate, and the quality of your sleep can all affect the results," adding that "even the same person can get different results depending on their physical condition and lifestyle at the time of the test."

Different types of tests can also produce different biological ages for the same person. Morgan Levine, the researcher who developed PhenoAge, said that when one person takes multiple types of biological age tests, each yields a different result — because each test measures slightly different biological characteristics and uses different datasets to establish average aging benchmarks for a given age group.

Levine said she hopes "people won't place too much significance on the number that comes out of a test result."

Another limitation of biological age tests is that the samples they analyze may not adequately reflect the body as a whole.

Widely used DNA-based biological age tests primarily analyze DNA extracted from white blood cells. Changes in white blood cells, however, cannot be taken as an accurate reflection of how other organs — such as the brain, liver and pancreas — are aging.

Tony Wyss-Coray, a professor of neurology at Stanford University, said that "while we can measure changes in blood cells, we cannot see what is happening in the neurons of the brain, liver cells, or pancreatic cells."

The New York Times said that while biological age testing is developing into an important tool for understanding the aging process and studying the effectiveness of treatments, it is too early to treat it as an absolute standard for judging individual health. The paper said experts stress that "rather than fixating on the numbers from test results, it is more important to practice proven health habits such as exercise, a balanced diet and quitting smoking, and to identify real risk factors through regular checkups."

Experts also note that one-time tests have significant limitations in providing meaningful health information.

Raghav Sehgal, research director at the Marcus Institute for Aging Research at Harvard Medical School, called biological age testing "the future that preventive medicine is ultimately trying to reach," but added, "we are not there yet."

Taking the same test repeatedly over a long period, however, may help track changes in health. Higgins-Chen said "aging is a process that unfolds over a very long time," and that "the true value of these tests lies in capturing when and how health changes over the course of years."

For those who want to assess their health now, experts say conventional routine checkups remain more useful. Mohammad Arfan Ikram, a professor of epidemiology at Erasmus Medical Center in the Netherlands, said "I would recommend getting standard tests first — things like cholesterol and blood sugar," adding that doing so "also lets you identify problems you can take direct action to address."

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