The Trouble with Trauma (and Post-Traumatic Stress Disorder)

I'm reading a book right now called The Night Strangers, a novel by Chris Bohjalian.  It's a pretty standard ghost story, but at the center is a pilot who has survived a plane crash in which most of his passengers died.  He's suffering pretty severe PTSD, and the ghost part goes on from there.

The reason I mention the book is that it's gotten me thinking about PTSD and trauma, and what constitutes trauma.  Clearly, a plane crash would constitute as trauma for just about anyone; it's understandable that someone who survived something like that would have some lingering issues.  A while ago, though, I wrote about postpartum PTSD, and how a lot of people don't think about how childbirth could be traumatic and cause something as serious as PTSD.  I know, however, that I did have PTSD after my first daughter was born, even though I didn't realize it at the time.

The thing is, I know someone else could have gone through the same childbirth experience that I did, yet not experience trauma.  Similarly, a few years ago I was in a car wreck with my husband and baby in the car, in which my new car was almost totaled, and had no lingering issues from that at all.  I know other people have gone through similar wrecks and probably did experience PTSD.

The US Library of Medicine says that PTSD can occur when someone has "seen or experienced a traumatic even that involved the threat of injury or death."  Seems pretty straightforward.  The definition mentions incidents like war, assaults, abuse, and terrorism as "traumatic events."

In a weird stroke of synchronicity, however, I was reading some of the stuff about this whole Penn State debacle, and there was a report of a janitor who saw the coach in question molesting a young boy.  The janitor was a Korean War vet, but said that what he saw between the coach and his victim was something he'd "never forget."   Clearly, witnessing the abuse of a child was more traumatic to this man than what he'd seen in the war, but that seems to counter the previous definition of PTSD.

What makes one person's trauma another person's mere experience?  And, what makes one experience traumatic to a person, versus another?   So often, when you have a traumatic experience, people in your life  tolerate your PTSD to a point, and then, when it seems like enough time has passed, everyone assumes that you should "get over it" or "get through it." 

Unfortunately, I think when you experience a trauma severe enough to cause lingering issues, it's something that stays with you for a long time -- maybe forever.  It may be something you can manage with therapy or other coping mechanisms, but it's something that stays in your brain, like the janitor in the Penn State scandal said.  It's something you carry with you for a very long time, maybe forever, and it may be a mystery why one experience is a trauma and another is just an experience.