Hello Theo, welcome to the NeuroTalk Support Groups.

Sorry this is so long but I cannot write this out shorter, it's the way my brain works.

Were you actually diagnosed by a doctor as having DDD (dp/dr disorder) as defined by the DSM-5? There are many different differential diagnoses to be ruled out first.

It's my understanding this condition would be extremely rare and that transient feelings of depersonalization and derealization can occur in a large proportion of the population for many, many different reasons. "Other Medical Conditions" is an exclusion for a diagnosis of DDD or dp/dr disorder as you called it.

Experiencing episodes of depersonalization and derealization and having DDD (dp/dr Disorder) would have different causes, different treatments and thus different potential outcomes.

I read an article on Brainline regarding depersonization and derealization after head injury. Many years ago when I was dealing with PCS I also experienced the feeling that everything was "surreal" or "unreal". It was transient although it did make me extremely anxious and depressed at the time because it totally changed my ability to interact with the world. I'm pretty sure that this is the same experience that many other PCS patients have talked about here. PTSD is also talked about there.

Interestingly I experienced the exact same feelings during my year long brain fog after I had Gamma-Knife stereotactic surgery for brain metastases, so I guess it was from the radiation. Brain injury. Was transient.

I also experience a certain amount of dp/dr during the prodome stage of my migraines. It alerts me that I have migraine coming.

I have also seen this dp/dr in a couple of patients after Stroke. It can also occur in people with Epilepsy. Is transient.

I've also experienced it and have seen it in patients taking certain psychotrophic medications (in my case an SSRI long before head injury) and I read that it occurs with consuming certain drugs. Was transient.

I'm not sure what country you live in Theo. I'm interested in the type of doctors you have seen. Also if you are in different area then the ICD 10 criteria could be different. I had to stop reading...

Why Does Everything Seem So Surreal After Brain Injury? | BrainLine

Depersonalization in the DSM-5 | Psychology Today

DSM-5
Depersonalization/Dereallzation Disorder - Diagnostic Criteria 300.6 (F48.1)
Page 339 of 970 in pdf (lots of scrolling ugh)
DSM-5 pdf

Depersonalization/Derealization Disorder - DSM-5 Code 300.6