People here are so quick to poo poo the evidence afforded by anything but double blinded placebo controlled studies, and then turn right around and make claims with no backing at all. And a bunch of people mod them up for it.
This is perhaps the wrong time to voice this complaint - because rejecting the claim made by the dance instructor is the obviously correct response. The study just doesn't say that frequent dancing causes a 76% reduction in the risk of dementia. Even the people who wrote the study would cringe if they saw their work being used to make that claim! This isn't "poo poo", it's "WTF?"!
Frequent dancing causes a 76% reduction in the risk of dementia. The benefit seems to be from freestyle social dancing, though I don't think that part is as well-verified. The benefit seems to be from making large numbers of quick decisions.
I wonder if playing jazz has similar good effects.
For something a little geekier, Shiva Nata, a system of keeping the mind fresh by doing more and more complex movements. The author of the blog is a silly person, but the system seems to be for real.
Edited to correct html which was entered in the text field instead of the html field. It wouldn't surprise me if having to deal with electronics and computers tends to prevent dementia, considering the number of fiddly and changing details one has to deal with. Or is fun required?