Do Personality Traits Predict Cognitive Decline?

Interesting but not surprising. People who are quite engaged with their surroundings and other people, and juggling and involved in many interests and activities, would have more active brains. Just like doing crossword puzzles, learning a new language or skill is said to help ward off dementia.

I once read a study where they had measured the brain waves of people when they were reading, conversing with others, and watching TV.
Brain waves were most active when reading, next when conversing, and the brain waves when watching TV were almost indistinguishable from being in a coma.
The interesting thing was that it didn't matter whether someone was watching an educational show, like discovery channel, or some stupid sitcom, brain waves were almost flat because it's a totally passive activity in which your brain does not need to work.