And actually, I'd like for Anthony to weigh in on the "not everyone with PTSD dissociates" line. It was my understanding that everyone with PTSD DOES dissociate in that a flashback is dissociation from the present that requires grounding.
Not everyone with PTSD dissociates outside the normal boundary of what every human being dissociates. You don't have to dissociate to have PTSD.
Dissociation is actually a learnt behaviour, when it goes to the extent of beyond normal. Keep reading why!
Everyone dissociates, from forgetting what you just said, to automatically driving from point a to point b, and not really remembering in-between. What isn't dissociating, is if you went to the dentist, are scared of a dentist, thus you intentionally push yourself elsewhere... that is not dissociating, that is an avoidance strategy that is intentional.
The key element of anything to do with dissociation is, "an unconscious act".
The moment you consciously do something, that is avoidance. Hence, being the difference between them.
Behaviour can be a conscious or unconscious act... still it is learnt, not inherited or genetic.
Like anything, for it to become an actual disorder of itself, it must go outside the normal spectrum of normal, it must impact your daily life enough that it creates problems for functioning in either of several areas.
DID - Everyone has multiple voices / elements within. Confident, shy, doubtful, avoidant, etc. We all have sub-personalities (alters), knowingly or not, everyone has them. They are normal... though they are not distinctive. What differentiates DID, being extremely rare and currently over-diagnosed due to confusion of wording, is that in 97% of cases, the person has severe childhood abuse where they have literally grown-up having to have all these different identities in order to survive. They have integrated through to adulthood, again, beyond normalcy of what everyone already has.
IMHO, 99.9% of people diagnosed with this, are misdiagnosed. People with it can take that as they see fit, but I hold the same opinion on DID as the majority of the mental health industry does.
DDNOS - This is typical when the dissociation is simply so much of a problem, outside the realm of acceptable dissociation as part of PTSD, that they then diagnose it uniquely, as it interferes individually to the extent it incapacitates the person beyond PTSD incapacitating the person. In other words, you have two things primarily incapacitating you.
Flashbacks - Whilst flashbacks are a dissociative state, they are of themselves. Flashbacks are also very rare, and very few people with PTSD actually have flashbacks. Flashbacks are a literal reliving of the event, not just a passing moment, thought, memory or trigger, which many confuse them with. They're either a replay in your mind of the event or they're an emotional replay through feeling... again, not to be confused with a moment of panic, trigger or fleeting memory, as they are longer lasting than those instantaneous moments.
Dissociation is often found in those who have been sexually abused as children, most commonly when the abuse was by a primary care giver. That is where dissociation becomes learnt due to the nature of the relationship and traumatic aspects of what that person is doing. The majority of highly dissociative persons come from childhood abuse due to a primary caregiver. It is a minority outside this scope.
Soldiers are common to have flashbacks to specific emotional events, as they are less emotion bound, thus flashbacks are more sudden and longer lasting due to a soldier primarily using avoidance as their coping strategy, so they suffer flashbacks instead of outright dissociation.