Brain Exercises Ward off Alzheimer's

This Columbus Dispatch article entitled "Brain Exercises Might Ward off Alzheimer's" discusses research that indicates individuals who participate in life-long cognitive exercises have lower amounts of the protein that contributes to Alzheimer's disease in their brains. It also discusses several local programs and local research (to Central Ohio) that are looking at cognitive exercise as a preventative factor against cognitive impairment. How do you think brain exercises might ward off Alzheimer's? What types of brain exercises would you be willing to do?