Don't buy the test

The most useful sentence in Eric Topol's piece on biological aging clocks is the one telling you not to spend money. Aging clocks are already being sold direct-to-consumer, mostly epigenetic, without standardization or reliability and at considerable expense. His advice is plain: he would suggest not buying any of these tests.

Hold that against the rest of the argument, which is genuinely exciting. Large-scale proteomics has found three waves of aging clustering around 34, 60 and 78. Organs inside one person can differ by roughly a decade, and in a British cohort all born the same week in 1946, that spread was visible by 63. About one in four people carry accelerated aging in at least one cell type. People whose brain astrocytes aged fastest developed Alzheimer's at 12.6 times the rate of those whose aged slowly.

So the science is real and the product is not. That gap is where families lose money, because the interval between a finding being true and a test being trustworthy is exactly the window the wellness market sells into. A caregiver reading about organ clocks this month will find something to buy this month. It will not be the thing in the study.

What survives the caveat is the frame, and the frame is free. "He's 86" explains nothing and suggests nothing. "His brain is aging faster than his heart" is a different conversation with a doctor, and you can have it without a test.

The question a family is actually asking has never been how old he is. It is which part is going first, and how much warning that buys.