The clincher was the link between memory improvement and cathepsin levels, Duzel says.
“Those individuals that showed the largest gains in memory also were those that had the largest increase in cathepsin,” he says.
Of course, cathepsin is probably just one of several factors linking exercise and brain function, van Praag says.
“I don’t think we have fully explained how exercise improves memory,” she says, “but I think we’ve made a significant step forward.”
But cathepsin has a dark side. It’s produced by tumor cells and has been linked to the brain plaques associated with Alzheimer’s. So, trying to artificially raise levels might not be a good idea, van Praag says.
In mice, monkeys and people, exercise releases a protein called cathepsin B. And as blood and brain levels of this protein rise, memory gets better. But the protein has a dark side, too.
Source: Cathepsin B, A Protein With A Dark Side, Links Memory And Exercise : Shots – Health News : NPR