A young body has a mechanism that drives cells to grow and divide. Think of it as the gas pedal in a car. When you are young, you need it to move forward. But in old age, the same mechanism no longer helps; it accelerates wear and tear. Scientists have long wondered: if you ease off that pedal in the elderly, could you extend healthy life? The problem was finding a safe way to do it, something you could simply add to food.
The results were good. In mice that received the compounds, memory stayed as sharp as in young animals. In males, blood pressure dropped and blood sugar improved. In females, fur barely grayed, and overall weakness fell threefold. One of the compounds, NVP-ADW742, compressed the period of illness: the mice lived in good health for 93 days longer, although total lifespan did not change.
But the compounds themselves are not yet suitable as medicines. One is unstable and causes bleeding; the other is poorly absorbed and can disrupt heart rhythm. Still, it is now clear that slowing the growth signal in the elderly is possible, and it improves health. What remains is to build a safer brake. The gas pedal of old age can be eased off, if you find the right way to do it.
In female mice receiving IGF1R inhibitors, the coat remained black and glossy until death, whereas control animals turned gray. This brings to mind the folk observation that stress and growth hormones accelerate graying.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.