An alternative explanation for the finding is that high IQ people are more likely to have mentally stimulating work and can lose more of their mental capacity w

An alternative explanation for the finding is that high IQ people are more likely to have mentally stimulating work and can lose more of their mental capacity without appearing demented. You can't easily change peoples' jobs, but you could do a randomized trial where the treatment group is encouraged to take up a mentally stimulating hobby, say Scrabble, chess or bridge. It would be great if taking up such a hobby staved off dementia, but I am skeptical that it does. 'Researchers have found that the more people use their brains at work, the better they seem to be protected against thinking and memory problems that come with older age. In a study of more than 7,000 Norwegians in 305 occupations, those who held the least mentally demanding jobs had a 66% greater risk of mild cognitive impairment, and a 31% greater risk of dementia, after the age of 70 compared with those in the most mentally taxing roles. “It really shows how important work is,” said Dr Trine Edwin, a geriatrician and postdoctoral fellow at Oslo university hospital. “It’s important to go to work and use your brain, and to use your brain to learn new things.”'