Timothy Salthouse of the University of Virginia notes that "there is no convincing empirical evidence that mental activity slows the rate of cognitive decline," a message that stands somewhat opposed to Nintendo's Brain Age campaign. "The research I reviewed is just not consistent with the idea that engaging in mentally stimulating activities as you age prevents or slows cognitive decline." While the rate of mental erosion is labeled as constant by the study, it suggests that the minds that remain sharp are merely dropping from a higher point. The higher you start, the longer it takes you to hit bottom.
The mental usefulness of the innocent crossword puzzle also comes under
Still, the article points out (perhaps obviously so) that the greatest benefit of games like Brain Age is that the constant training improves an adult's ability to perform the given task well. One thing's for sure--we'll soon be glorified experts at saying "Blue!"
[Thanks Vlad! Linked article requires membership to access.]