We all know anecdotally that exercise can help beat depression, which some people with PCS have.

An article in the New York Times recently reports that scientists have found that exercise increases levels of brain-derived neurotrophic factor (BDNF), which may play a role in improving memory and recall. BDNF levels are also associated with the ability to perform or complicated tasks.

http://well.blogs.nytimes.com/2011/1...its-the-brain/

By extension, it suggests to me that there's something to staying as active as possible as part of recovery from a concussion or treating PCS.