Multiple Personalities Support Group
Dissociative identity disorder is a diagnosis described as the existence in an individual of two or more distinct identities or personalities, each with its own pattern of perceiving and interacting with the environment. At least two of these personalities are considered to routinely take control of the individual's behavior, and there is also some associated memory loss,...
There are many dr.'s and therapists who do not believe this condition exists, either. Your son is only 20, and still, the world's point of view from his eyes is relatively narrow and simple, just because he is still so young. And some people never get to be that mature at all. They have the most potential for harm, in my opinion, as they think they know the simple and pat answers, and life in general just isn't like that a lot of the time.
Another reason why your son might be easily swayed into believing there is no such thing, is because your illness is so close to home, and it's terrifying to have to come to terms with the idea he could possibly have those problems, too....(even though it's not inherited, it is often passed down behaviorally, even though not usually intended)
If he's open, you might find and suggest some reading material about it (with a fair warning to him it could stir up some of his own emotions) Or, if you have a therapist and your therapist is willling, perhaps you could have him come to a few sessions to talk about it and answer some of his questions.
One small hint that he might be in a bit if denial himself, is that you said he doesn't believe in DID, which is reasonable, as it is very contraversial in general. However, PTSD is a well-known and well accepted diagnosis (and at least most people can accept and perhaps even identify with that concept on some level)...perhaps your son has some of his own issues he's hiding from himself as well.
So if you treat him with that understanding, it's a lot easier to be patient with him.
If he's not open to further discussion and/or education, then it's probably best to avoid that subject, and if he brings it up, remind hiim how little he knows about it, and he should not judge you, no matter how much he knows, or doesn't.
I think the key lies in helping him understand why you can't manage an average day. (and for me, it's also, why sometimes I can, and sometimes I can't)....if he's not able or willing to come to that understanding, then it's his pain he's likely to be hiding from, not yours. Or at least, as well as yours.
hat said, i doubt anyone here is faking. there have been a few trolls over the years, and some probably exaggerate, or make up some symptoms but that is part of the pathology. and just because a person does that about one thing doesn't mean they are dishonest about the balance of their experience.
one of the reasons people think those who have dissociative disorders/ptsd and related disorders are faking is the reasons such disorders develop. they are horrified by the trauma and don't want to believe it happened, it's self protective. and for close family members it can also be fueled by guilt for not intervening.
in the situation where it's a person's child i'd guess that it is the child's desire, regardless of their age, to have a healthy parent. denial is a very potent motivator. it very sad for both the parent and child.
Hugs,
Wistala