Experts are reshaping the way Post Traumatic Stress Disorder (PTSD) is viewed, in part because a growing number of US soldiers who served in Iraq and Afghanistan have sought treatment for it.

New research has established a link between PTSD and physical damage to the brain. In fact, the Canadian military has started calling it an "injury", instead of a disorder.

Al Jazeera's Tom Ackerman reports from Washington, DC.