i'll just say it, your suspicion is probably correct. antipsychotics cause reduction in brain matter over time with long-term use. in fact its possible that the reduction of brain matter seen in people with schizophrenia or bipolar is actually due to the medications they're given, not the condition itself. i would share a study i found on this but my phone is shit and im on low data, but i recommend researching it yourself.
that said, i have dx'd bipolar with psychosis myself, but i think i more likely am schizoaffective. idk if i have brain damage, it feels like i do, but ive also fucked up my brain with drug use so i cant say what the cause is for sure