Childhood is like photographic film: even if the frames are bad, they don't disappear, they leave scratches. Scientists have found a way to see those scratches in the blood. They asked people about difficult childhoods and measured chemical marks on DNA. These marks work like a clock showing how much older the cells are than the person themselves. It turned out that in people with a tough childhood, the clock runs fast. In women with the most severe trauma, cells looked on average 2.4 years older than they should.
Then the scientists checked how this relates to pain. People with a tough childhood are 3.8 times more likely to suffer from chronic pain. In women, the link was stronger. The aging clock explained only a small part of this link, and after accounting for smoking, that explanation vanished. So the main path from childhood trauma to pain runs through behavior, not only through biology. This matters: if you help someone quit smoking, you can slow aging a little and lower the risk of pain. But childhood still leaves its mark, and that mark can be measured in the blood.
The GrimAge clock was trained to predict mortality, not age, so its acceleration in people with severe childhood adversity literally means their cells look "older" in terms of the risk of dying earlier.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.