just a bit of info on the original posters question... there is no disorder in the DSM 5 called dissociative subtype ptsd.

whats happening is under the diagnostics for PTSD the diagnosing psychiatrist must .....specifiy.... whether the person has dissociative symptoms and whether those symptoms are depersonalization or derealization symptoms.

example

client ...Amandalouise
diagnosis.....PTSD
please specity....
does this client show dissociative symptoms...yes
are these dissociative symptoms depersonalization yes
are these dissociative symptoms derealization symptoms....yes

now to understand this...... depersonalization and derealization symptoms are opposites, by that I mean depersonalization are feelings about inside one self while derealization is feelings that things outside one self

examples

feeling like I am numb spaced out disconnected, feeling that I am moving too slow, feelings like I am not all there is depersonalization

feeling like the world looks foggy, feeling those around me are moving too slow or too fast, feeling like that plant over there has no connection to me is derealization.

sometimes when people have their PTSD symptoms (anxiety\panic\ nightmares\ flashbacks\sleep problems....) they also feel the depersonalization or derealization symptoms.

as a result of this now the diagnosis of PTSD requires a treatment provider here in america to.....specify....if there are any dissociative problems and if they are depersonalization or derealization.

some locations call this subtyping and other locations here in america do not. my location does not call it subtyping. we call it what the DSM 5 calls it... specifying.

to find out if your own PTSD diagnosis carries the specification of one or the other or both specifiers you will need to contact your treatment providers. they will let you know what your test results and files say on this issue.