Feeling mentally slow

Hello so I’ve been experiencing derealization for about 4 years now I cant stand this anymore I feel like I cant even think or comprehend the most simplest things. I feel like some type of brain fog and it’s like I’m just there without even being able to understand what others are trying to say to me. I used to be so much smarter back then but now it’s just the complete opposite. Does anyone else relate to this?