It's the same thing. But it's because what you're describing is an extinguishing mechanism that works. That's the normal mechanism.
First of all, I find it very interesting--it's not fun, but it's very interesting--that such a high proportion of the population develops post-traumatic stress disorder. It makes us wonder why they have it and why there's a susceptibility. I believe there's a genetic buildup. There might have been a protective role at a certain point in developing that. It may have been protective to ensure avoidance of certain stresses by human beings—and I'm talking about millions of years ago—but it stayed in parts of our genes. It's clearly no longer very useful.