Purely because you dissociate? Nope.
At the level, depth, & frequency you dissociated to? Maybe.
Diagnosis is tricky. Sometimes a severe symptom is just that; a damn severe symptom best explained as a facet of one (or more) disorder(s). Other times, it's best described as it's own disorder.
Does it make any difference in the end? Usually. Because different disorders have different treatment & prognosis.
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As an example;
I have two different kinds of pathological disassociation -that I know of ;)- one linked to PTSD & one linked to ADHD. I have to come at them very differently. The stuff that helps one? Makes the other worse. & vice versa. Do I have a disassociation disorder on top of those two? Probably not. Because there isn't a lot left over that isn't exceptionally well managed by either one or the other's bag of tricks (treatments, tools, therapies). But it could very easily look like I had a dissociative disorder if we didn't already know about my 2 comorbids. I test reeeeally high for dissociation. Much higher than either PTSD, or ADHD, explain on their own. Add them together, though? Yep. Pretty easily explained by both. Especially when they cozy up & play so nicely together :wtf: ((When that happens I have to use both sets of tricks. Ugh.))
Worse? I get secondary symptoms from PTSD which long story short mean I will be starving (literally) & in severe/chronic sleep deprivation. ... Gues what each of those 2 things come along with? Yup. Disassociation.
So if I'm doing reeeally badly? Pfft. Planet Earth is soooo not where my head is at. I need food, and sleep, and ADHD tricks, and PTSD tricks. To even begin to be really present.
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This sort of thing is why we tend to repeat ad naseam that none of us can diagnose. There are sooooo many different possible roads to the exact same symptom set. Including physical causes (like food, sleep, illness, imbalance, injury, etc.), neurological (TBI, etc.), psychological (whole lot of disorders out there), environmental/chemical (think meds; but there are other things, like low oxygen or compressed environments, or particulates that coal miners or city dwellers are dealing with) , or situational (grief is a good example). <<< And these are really just the tip of the iceberg in hundreds of data points that make up an accurate diagnosis. So you aren't being treated for the wrong thing.
So maybe it's a stand alone disorder on top of your PTSD.
Maybe it's a really severe symptom of your PTSD.
Maybe it's being caused by something else (physical, neurological, environmental, etc.)
Can it be treated? Yep.
Find the cause.
All causes have treatments. Some better, or faster, or easier, or more profound than others. But when you find the right cause? Throws open a whole world of things that actually work.