The body is a whole, and nothing you do or eat or take affects only one part. One false dualism that many people have is brain/body.
What affects the body does affect the brain as well, including exercise. A new study found that people with early Alzheimer's had significantly less brain shrinkage the more they exercised. There's a lot to be learned still, but their are indications that exercise helps reduce production of beta-amaloid, the protein that aggregates in the brains of those with Alzheimer's. Many scientists also believe that exercise causes the release of nerve growth factors in the protein, contributing to the growth of healthy brain cells.
So its really pretty simple. The core building blocks of the High Performance Living program for optimum health and functioning of the body and brain are:
1. Eat a Paleo diet. See www.ThePaleoDiet.com.
2. Exercise
There's of course much more, but these two items, in the order above, are the most critical.