There are tests now that claim to measure how old you really are. Not the number on your birth certificate, but your biological age, the idea being that two people born on the same day can be aging at different speeds, and that a blood or saliva sample can tell them apart. It starts with a discovery from fifteen years ago, that chemical marks on your DNA shift as you get older. Since then the clocks built on it have moved fast, from reading your age, to forecasting how long you have left, to scoring each organ, to scoring individual cell types from a single vial of blood. So what does one of these numbers actually measure, how good have they become, and would one handed to your doctor change anything about what happens to you?

0:00 – Can You Really Measure Your Age?

1:04 – The Cheek Swab That Started It

4:00 – Reading Death, Not Birthdays

5:45 – The Hidden Flaw

7:51 – Your Organs Age Differently

8:36 – 11 Ages, One Blood Draw

10:06 – 40 Clocks, One Vial

11:36 – The Missing Proof

14:15 – The Verdict

IN THIS INVESTIGATION

-How a test can land within a few years of your real age, and why that accuracy is the catch.
-The one number buried inside a biological age result that's supposed to carry all the meaning, and what happens to it when you test the same blood twice.
-How a birthday-guessing tool turned into a blood test that scores individual cell types, one vial at a time.
-An Alzheimer's signal sitting in an ordinary tube of blood, and the brain cells that may decide who develops the disease and who doesn't.
-The four things an aging clock has to clear before it belongs in a doctor's office, and where today's tests actually stand.

REFERENCES

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-Lu et al. DNA methylation GrimAge strongly predicts lifespan and healthspan. Aging (Albany NY), 2019. PMID 30669119
-Sugden et al. Patterns of reliability: assessing the reproducibility and integrity of DNA methylation measurement. Patterns (N Y), 2020. PMID 32885222
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NOTE: This video is educational content. It is not medical advice.