You may enjoy this book.
The far side of madness https://www.amazon.com/dp/0133030245/ref=cm_sw_r_cp_api_i_gFbpFbC0RSVTJ
It seems as though you're looking for fiction but this book may interest you.
I also recommend the first result on this page - the pdf - the inward journey. It's a comparative mythologist's assessment of schizophrenia. In it is an account of one man's journey into psychosis. Joseph Campbell then compares that same journey to myths showing an odd an interesting connection between the two. I gave away my copy of the book that it comes in, myths to live by, but i believe he may reference John Weir Perry's book as well.
https://www.google.com/search?q=the+inward+journey+campbell&ie=utf-8&oe=utf-8