PKD himself wrote a semi-autobiographical story (“A Scanner Darkly”) about mental breakdown due to drug use. It’s a haunting book and the feeling it evokes has stuck with me since I read it about ten years ago.

https://en.m.wikipedia.org/wiki/A_Scanner_Darkly

As with many PKD stories, it was turned into a film, which although I have not seen it, is technically notable for being entirely rotoscoped.