Nancy Kedersha/UCLA/Science Photo Library

For the first time, a cocktail of drugs has been used to make new neurons in the brain. If the research, in mice, translates to humans, it could give us ways to repair the brain in Parkinson’s and Alzheimer’s disease, or after a stroke or brain injury.

The brain is notoriously bad at regenerating lost tissue. Although many other tissues and organs renew themselves throughout our lives, adult brains simply do not grow new neurons – or so we used to think. We now know that some brain regions do seem to keep forming a …