Mark's comment explains why I don't like the following note in the Mayo Clinic's writeup on PCS symptoms:

"Some experts believe post-concussion symptoms are caused by structural damage to the brain or disruption of neurotransmitter systems, resulting from the impact that caused the concussion. Others believe post-concussion symptoms are related to psychological factors, especially since the most common symptoms — headache, dizziness and sleep problems — are similar to those often experienced by people diagnosed with depression, anxiety or post-traumatic stress disorder. In many cases, both physiological effects of brain trauma and emotional reactions to these effects play a role in the development of symptoms."

http://www.mayoclinic.com/health/pos...SECTION=causes

The second sentence underlined above seems to imply support for the view that PCS is simply a psychological phenomenon. While I believe that there are psychological aspects to PCS that should be attended to, I find this claim to be a bit misleading (at best). At worst, it reinforces the misconception apparently held by many MDs that PCS (especially after some weeks or months have passed) is largely or entirely "just in your head."