Which comes first? Higher brain activity or Alzheimer's

Reports on this study linking job-difficulty level with Alzheimer’s are all over the news today. “Those with high levels of leisure activity had a 38 percent lower risk of developing dementia, even when controlling for other risk factors, including ethnic background. Leisure activities included reading, going to movies, taking walks and talking with friends.”

But no account was taken in the study of whether the people might not have assumed more challenging job responsibilities as they grew older because they were already developing the beginning stages of the disease. An earlier study seemed to support the idea that a brain reserve could be built up (from formal education and other learning experiences) that might serve as a backup when the disease begins to manifest.

Clearly it can’t hurt to exercise your brain as well as your body.