Some choice tidbits from:
http://www.nytimes.com/2011/02/08/healt ... f=homepage
(it's short, read the whole thing)
In healthy adults, the hippocampus — a part of the brain important to the formation of memories — begins to atrophy around 55 or 60. Now psychologists are suggesting that the hippocampus can be modestly expanded, and memory improved, by nothing more than regular walking.
After a year, brain scans showed that among the walkers, the hippocampus had increased in volume by about 2 percent on average; in the others, it had declined by about 1.4 percent. Since such a decline is normal in older adults, “a 2 percent increase is fairly significant,â€
While it is hard to generalize from this study to other populations, the researchers were delighted to learn that the hippocampus might expand with exercise. “And not that much exercise,†Dr. Erickson pointed out.