Interesting, though I believe of little overall significance. It concentrates on fear alone. PTSD is already factually know to be much more than this. The study uses words such as 'usually' and other broad terms, which mean there are exceptions.
It incites only fear of a singular stressor. What about a more low level, constant fear structure that isn't so much fear, but combined with growing-up with an abusive parent? You have fear + love + other emotions, all towards the abuser. What about combat zones, when you don't have a singular fear, but more there is always danger around you in which you simply accept.
I can poke many 'what ifs' into that information already, based on other knowns.
Many people who obtain PTSD many years after the fact, cite they enjoyed the adrenaline rush of an exciting event in their life, yet don't understand how so much later that same moment that was exciting to them is now traumatic. The brain, combined due to time, changed the perception. How does that have affect in relation to the amygdala processing fear immediately after the event? Or more to the point, stopping it from processing an abundance of emotion that overwhelms us, as cited in this finding!
Too many questions IMHO... too many 'what ifs' as well. This finding seems to be heading towards another pill.
This is why experts stopped looking at the amygdala and hippocampus as a solution for PTSD, because PTSD itself is centrally located in the pre-frontal cortex. It has surpassed those areas of our brain.