A trial that enrolled 2,832 older adults found that ten years later, the group given memory training was no better at memory than the untrained controls, which is an awkward result for the crossword-a-day theory of keeping a strong mind

The advice to do a crossword every day to keep your mind sharp is one of the most repeated pieces of folk wisdom about aging, and it is the one with the weakest evidence behind it. That does not make it bad advice. It makes it different advice from what most …