I hate these "science journalists." Not one of these asshats ever bothers to cite the freaking paper. It's scientific malpractice to not give credit to the guys who did the work. If I did that shit, I could be up against an ethics review to explain how I wasn't trying to pass off someone else's work as my own - academic death.

Had to dig. Link to the paper. It's Nature, so of course, it's paywalled. I miss being a student. Access was always free. https://www.nature.com/articles/s41586-022-04722-0

Short version: They found a protein called serum response factor (SRF) that makes neurons make new connections, a biochemical signal to induce the brain to become plastic (ie to make new connections between neurons to accommodate new knowledge and skills). They found a second protein called fibroblast growth factor (fgf17) which causes SRF levels to increase. When given to old mice, they saw activity levels consistent with youthful brain function. It should be noted that in young brains, fgf17 actually impaired cognition, so this may be a double-edged sword of sorts.

Lots of interest here because fgf17 is now a potential new drug if they can find the human equivalent and show it works in humans the way fgf17 works in mice.

None of this has anything to do with adrenochrome.