It's all in their heads

"A concussion is more a mild form of traumatic brain injury in which the brain is exposed to abnormal forces that result in transient neurological dysfunction," Ellis says. "But ‘mild traumatic brain injury’ is a bit of a misnomer."

Source/more:

http://www.winnipegfreepress.com/arts-and-life/life/health/its-all-in-their-heads-390878351.html

Chronic Pain Can Cause Long-Lasting Damage To Your Brain

Chronic pain can damage and change your brain. If you live with chronic pain, you will know how devastating and wide-ranging the effects can be on your mental processing speed, your mood, and your memory.

Source/more:

http://www.lifehack.org/450898/chronic-pain-can-cause-long-lasting-damage-to-your-brain