Two academic journals weigh in on the tired subject of games fighting dementia:

Neurology finds that regular cognitive activities, such as puzzles and games, help fight dementia. (source)

Journal of Educational Psychology finds that linear board games that require you to count along a path toward an ending space – as opposed to a) circular board games, examples of which will not be mentioned here, or b) simply doing counting skills, such as counting poker chips – not only increases basic math skills in children, but increases their ability to learn new math skills. (source)

And Escapist Magazine so regularly pimps board games nowadays, that I now welcome them to the officially converted. Allen Varney pimps Dominion. (source)