Key Takeaways
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How old are you, really? Your birth certificate gives one answer. The cells in your body may be telling an entirely different story.
Researchers have debated how much of a long life comes down to your genes versus your habits. But it’s not simply one or the other, and how we measure your age can help us understand your health long before your next birthday. Your organs, and even individual cell types within them, can age faster or slower than your calendar age suggests. And for the first time, scientists are starting to measure that directly.
The Genetics of a Long Life
Genetics has always been part of the longevity story. Some estimates suggest up to about 50 percent of lifespan can be attributed to genetics, particularly once you set aside causes of death like accidents or infections.
The clearest example is the APOE gene. The e4 variant is linked to a higher likelihood of late-onset Alzheimer’s disease, while the e2 variant is associated with longer lifespan. Other genes, including FOXO3A, show up again and again in studies of people who live exceptionally long lives.
But genetics alone isn’t the whole story.
Aging in Waves, Not a Straight Line
A new review in Nature Medicine highlights research that’s challenging an assumption many of us have carried around without questioning: that aging is a slow, linear march through the decades.
But first, how are we measuring aging? Biological age isn’t tested with one specific method, instead a family of approaches that includes DNA methylation or “epigenetic” clocks (the original approach, measuring chemical tags on your DNA), proteomic clocks (measuring thousands of proteins in a tissue sample), and clinical biomarker-based models (based on standard bloodwork markers such as cholesterol or blood sugar) can be used.
When we use these methods we see that your body’s age doesn’t always line up with your calendar age. One proteomics study found something closer to three waves of accelerated change, clustering around ages 34, 60 and 78.
And aging doesn’t move at the same speed throughout your body. A landmark study built separate aging clocks for 11 individual organs, from the heart to the kidneys, using blood plasma proteins from more than 5,600 adults. This analysis found that nearly 20% of people had faster aging in one organ, and this aging was connected to organ-specific diseases.
Across multiple studies, faster aging in a given organ tends to line up with higher risk for the diseases tied to that organ. A heart that ages quickly has a higher risk of heart failure, and accelerated aging of the brain and blood vessels tracks with faster progression of Alzheimer’s disease.
Where Genetics and Biological Clocks Meet
Being able to measure aging in specific organs, and even at the cellular level, is beginning to allow us to combine genetics and biological clocks to make better risk predictions. Carrying the APOE e4 variant raises your predisposition to Alzheimer’s, but it doesn’t tell the whole story.
A recent study looked at the astrocytes, the cells that keep neurons nourished and healthy, of people with two copies of the e4 variant. The researchers found that people with faster aging astrocytes had 3 times the Alzheimer’s risk of those with normally aging astrocytes. And those with younger astrocytes had a lower Alzheimer’s risk even with the same genetics. In other words, knowing both how your cells are aging and your genetic predisposition for Alzheimer’s disease can tell you more about your risk than either measure alone.
What You Can Do
Biological clocks are still in the early stages of moving from research labs into everyday medical care. But research is showing associations between your lifestyle and biological age:
- Staying physically active, not smoking and limiting alcohol were each associated with slower aging and lower disease risk in a large study of more than 17,000 European adults.
- Lower stress was associated with slower aging in African American research participants.
- Better sleep quality was associated with a younger biological age in a study of more than 360,000 UK Biobank participants.
- Loneliness was linked to faster aging and more chronic health conditions in a study of over 1,300 diverse participants in the United States.
Direct measurements of your biological age can build on what you know about your genetics to tell you how you’re actually doing today. And your habits may change tomorrow’s outcomes.
Track Your Own Biological Age
23andMe’s Biological Age feature allows you to investigate your own aging clock. Using 13 blood-based biomarkers, a model estimates your biological age and flags which biomarkers may be pulling it away from your calendar age. It’s available to 23andMe Premium Ancestry + Total Health members through biannual blood testing, and it’s also available as a standalone blood test for other 23andMe members.
Curious how genetics and lifestyle fit into the bigger longevity picture? Read more in How Genetics and Lifestyle Shape Longevity.
