In the brain, as in an old house, different rooms age differently: in one the wallpaper has faded, in another everything looks brand new. Scientists have found a way to measure the age of each "room" — that is, each brain cell — by looking at how its DNA is packaged.
Researchers gathered data on 1.5 million brain cells from 357 people of different ages and trained a computer program to predict age from DNA openness. The program learned to do this separately for each cell type: neurons, helper cells (astrocytes), the brain's immune cells (microglia) and others. It turned out that age is predicted most accurately from neurons, and less accurately from astrocytes.
The most intriguing part: this "clock" works not only on the human brain. It managed to predict age in mice and even in zebrafish, although their DNA differs from ours. What is more, the clock showed that in Alzheimer's and Parkinson's disease brain cells age faster than usual, especially immune cells. So doctors and researchers now have a way to measure the biological age of cells and to test whether drugs can slow aging.
A clock trained on human prefrontal cortex cells managed to predict age in the zebrafish retina, an animal whose last common ancestor with humans lived more than 400 million years ago.
The idea of an "aging clock" that can be turned back echoes Oscar Wilde's novel The Picture of Dorian Gray, in which aging is transferred to a portrait, as well as the film Cloverfield Paradox, where accelerated aging is used as a dramatic device.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.