Normalizing Dissociation Part 2: Depersonalization

Hi kerri,
I'm glad you brought this up. Rather than respond here, I'm going to write a post about it. For now I'll just say I can understand your frustration. And for what it's worth, anyone who is incapable of seeing that just because dissociation is normal doesn't mean Dissociative Identity Disorder is needs their own head examined, because their brain isn't working.

Keep in mind that I'm not a diagnostician or a clinician (something I know you already know, castorgirl, but I'm mentioning here for the sake of other readers).
In a word, no. Depersonalization isn't mentioned in the diagnostic criteria for either Dissociative Identity Disorder or DDNOS. But it's worth noting that diagnostic criteria sets exist to provide a synopsis of what symptoms must be present, and what symptoms must not be present in order to qualify for a particular diagnosis. When I look at the diagnostic criteria for DID, for example, I see only identity alteration and amnesia mentioned. To me what that says to clinicians is, "Hey if you see these two things together, you're looking at DID. There's more to it than that, but those two things in tandem are what set this disorder apart from every other psychiatric condition." The diagnostic criteria, in other words, are benchmarks that allow clinicians to recognize DID (and other disorders) when it lands on their couches.
I feel like I could be saying this better.
There is more to every condition than what's listed in their respective diagnostic criterion. We know, for example, that Dissociative Identity Disorder is strongly associated with early childhood trauma. But it isn't necessary to prove a history of trauma in order for a clinician to see that someone has DID. That wouldn't make sense, in part because loads of people experience early childhood trauma without ever developing a mental condition of any kind. So while trauma is a part of the development of DID, it cannot be relied upon to distinguish DID from any other psychiatric disorder. Identity alteration and amnesia, however, can.
Let's also consider how we define chronic depersonalization. I would argue that people without dissociative disorders experience dissociative amnesia far more often than they experience depersonalization. So if we say "chronic dissociative amnesia" we're talking about significantly more dissociative episodes than if we say "chronic depersonalization."
Then there's the fact that depersonalization is an umbrella term for a wide variety of experiences that can all be defined as depersonalization because, no matter how differently they manifest, they all boil down to a sense of detachment from the self. And I personally would argue that people with DID do experience that at a chronic level. But I would also argue that most of us have a difficult time recognizing depersonalization for what it is. Internal dialogues, for instance, with parts that you experience as "someone else" is a form of depersonalization. But I rarely see people refer to as such. And perhaps that's because they don't realize that's what it is.
This was long-winded. I hope the lack of brevity is made up for in clarity. I'm glad you asked the question. I'd imagine a lot of people would wonder the same thing.