It is almost definitely a predisposition/ anxiety related phenomenon. I have been through 2 LTC, one in the early 2000s and again about two years ago. I had forgotten how bad it was tbh and decided to give MDMA another shot.
The first time lasted around 8 months and then I felt recovered with no lasting cognitive/ depersonalization when I had reached the point of recovery. The 2nd time an SSRI pulled me out of it after about 6 Months. I have taken many drugs since but will never touch a serotonin releasing agent again in my life.
I am sure what I went through was a depersonalization disorder triggered by the after effects of MDMA use. It becomes your life, focusing on what you have done to your brain, and thinking about how you wish you could go back. Both times I fully recovered after I moved on from thinking like this, when I started interacting/ going out with friends again and living my life. I have no lasting problems and have consumed many other drugs without any lasting effects.
You haven't screwed up your brain. It's likely that you have a predisposition to an anxiety disorder that the serotonin depletion took a real toll on triggering the deporsonalisation... but as most have found, it will eventually come to an end and you'll be your old self again. You'll roll back to your old self and will likely even take drugs again. Just stay the hell away from MDMA and other SRA. They don't agree with you.
I know how unlikely this all seems given how strong the LTC is, it has to be brain damage right? I felt exactly the same way both time, but both times returned to my normal self given time. I had every symptom listed.
Notice how the faces you see on these threads change continually over time, with most being in the mist of a fresh full blown LTC. People recover, move on and forget about it. If you find a lack of success stories, it's not that people haven't got better, it's that they have moved on. I'm only here posting as I stumbled across this forum searching for something else, but I vaguely remember wheen reading threads like this trying to work out what I had done to myself was my life.
It was worse in the early 2000s, there was nothing like this thread where you could see other people had experienced this and you wheren't alone, and most had recovered. Happy recovery guys.
Both times I had MDMA. It was tested by myself with 4 different reagents. It was MDMA, and MDMA can and does trigger underlying anxiety disorders without a doubt.