The disorder comes in when those symptoms just don't go away.

PTSD, posttraumatic stress disorder, is a series of symptoms

that we all experience following a type of trauma,

where we experience a life-threat,

that is quite normal, it's helpful for our survival.

And the disorder comes in when

those symptoms just don't go away.

You go far beyond what's adaptive, what's going to be helpful

for your survival, they're no longer needed,

and yet something maintains the symptoms.

So, PTSD is very much a cycle of symptoms that get maintained.