The U.S. military has faced two epidemics over the last decade of war in Afghanistan and Iraq.
One is suicide. The annual rate of military personnel taking their own lives has doubled to about 20 per 100,000. That translated to a record 324 suicides in the Army last year.
The other is concussion, also known as mild traumatic brain injury, or TBI. The proliferation of roadside bombs has subjected thousands of troops to brain-rattling explosions.
Several studies have suggested a link between the two epidemics — that service members who suffered concussions are at greater risk for suicide.