Our bodies do not age at a uniform rate. The speed at which one organ ages can differ greatly from another due to a range of lifestyle, environmental and genetic factors. Conventional tests provide a single number for overall biological age, but they do not indicate which parts of the body are aging the fastest.
Now, scientists have developed a single blood test that can measure the aging of 11 different physiological systems, offering a more detailed and personalized look at how our bodies are changing over time.
For years, scientists have relied on epigenetic clocks, which use DNA changes in the blood to estimate biological age. They can give more insights than chronological age but are still not very precise. In a paper published in the journal Nature Aging, scientists describe how they set out to develop a new test for the aging status of different parts of the body.
A more precise look at biological aging
First, the team collected vast amounts of health data, including medical histories, blood tests, grip strength and other physical measurements, from about 7,500 people. They looked for clear links between blood-based biomarkers, such as cholesterol and blood sugar levels, and age-related conditions in several organs.
Then the team used machine learning to connect these findings with DNA methylation patterns from a single blood sample. DNA methylation is the process by which DNA adds or removes chemical tags that switch genes on and off, and which change over time. By training a computer to recognize these patterns, scientists created the Systems Age test, which can calculate a unique score for the biological age of 11 physiological systems. These include the heart, lung, brain, metabolic and immune system.
After training their model, the researchers tested it on blood samples of more than 8,000 people. They found that it was better at predicting specific diseases and aging-related conditions than the single-number biological age scores from older epigenetic clocks. For example, the test’s heart score was a stronger predictor of heart disease than a standard biological age test.
The researchers also found that individuals with the same overall Systems Age could have very different patterns of aging across their physiological systems. Knowing this could help doctors provide more targeted treatments to individuals.
“By providing system-specific scores, Systems Age may better pinpoint which age-related conditions individuals are at risk for,” wrote Morgan Levine, one of the authors of the study.
For example, if your immune system is aging faster than your lungs or heart, your doctor might recommend specific strategies to boost your immunity. Or if your heart score is high, a doctor could suggest lifestyle changes or medications to target cardiovascular health.
Written for you by our author Paul Arnold, edited by Lisa Lock, —this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive.
If this reporting matters to you,
please consider a donation (especially monthly).
You’ll get an ad-free account as a thank-you.
More information:
Raghav Sehgal et al, Systems Age: a single blood methylation test to quantify aging heterogeneity across 11 physiological systems, Nature Aging (2025). DOI: 10.1038/s43587-025-00958-3
The content is provided for information purposes only.