Because the DP feeling is tied in with your thoughts, there is the tendency to think that is a purely psychological phenomenon.
When you've recovered, like I have, you realize that it doesn't really matter what you think. If your nervous system isn't in a DP state, you won't think thoughts that have to do with unreality.
DP is a feeling, an emotional disorder and you only have those thoughts because you feel that way.
Nobody knows what causes DP, but it seems that it is something that happens to your nervous system as a result of bad drug experiences, organic brain disorders or some type of nervous system defect.
I do have momentary DP mini-relapses, but they are always traceable to some physiological cause, like not enough sleep.
When I had this momentary DP feeling, I remembered there was nothing I could do about it, and tried not to focus on it and let it die out, which it did after a few minutes.
It didn't accelerate into a DP panic attack, because I'm taking a drug (imipramine) that blocks these types of panic attacks.