Explaining PTSD to someone who doesn't have PTSD is like trying to describe the color "green" to a person who's been blind since birth. Sometimes we can get pretty close, like laughing off our fogs and brain farts as "the squirrels were at a rave". It's not unheard of for some folks to have PTSD but never show the symptoms, that's one of the possible affects. It is what it is. But what it is, changes from person to person.
People tend to go by what's visibly discernible, and PTSD is like any regular non-PTSD mental illness (bipolar disorder, schizophrenia, dementia, etc.) -- it's invisible to the outside world. You can't see it, smell it, hear it, touch it, taste it, it has no color or sound or shape. You can't wear it, you can't surgically remove it, you can't pop a pill, people can't see you have it because you ARE it.
The bench scene monologue of Men in Black absolutely nails it: "A person is smart. People are dumb."
Let that sink in for a moment. A person with PTSD is smart than 80 percent of the people he or she will ever meet, including those with more education. How does a god relate to mortals?
Correction: "A person with PTSD is smarter than 80 percent of the people he or she will ever meet, including those with more education."
Darn squirrels! :)