There is a new article on the Runner’s World website (http://news.runnersworld.com/2012/10/22/activity-linked-to-less-age-related-brain-change/) that talks about a study by Neurology showing that “people in their 70s with higher levels of physical activity have less brain shrinkage than their sedentary contemporaries”.
For me, less brain shrinkage is always a good thing. But I don’t know if I’m going to be able to run in to my seventies. I do feel a lot more confidant that I will be able to swim in to my seventies, swimming having a much lower impact on the body, overall. That’s why I’m cross-training now between swimming and running – it’s all for my brain!