Jinns may be a  traditional allusion to psychosis

أبه جِنَّة؟
Is he possessed by demons/jinn?
فأخبر أنه ليس بمجنون
They said: He is not mad/majnun.
It means that jinns may be a  traditional allusion to psychosis, or at least psychosis is a natural subset of supernatural possession.

https://sunnah.com/muslim/29/34