Soldier-scientist Kit Parker figured out what is happening at the cellular level when a blast wave hits the brain -- and it's not a mental health issue, it's a biochemical issue. The incredible and horrifying thing is that some service members have been blown up over and over, but "In 2009, Macedonia says, military doctors were still following the dictum: "If you don't have blood coming out of your head, if you don't have a penetrating injury, you're fine, everything's OK, have a nice day." Maybe PTSD is a physical change, not primarily a mental one.

I can believe it's a physical change. It's still not well researched.