I came across this book at the library, and read it. I was amazed at the insight offered in the book with regards to mental illness and demon possession. I will share the link to this book, Tormented: Eight Years and Back. It changed my perspective dramatically, and I would recommend this book highly to everyone.
http://www.amazon.com/Tormented-Year.../dp/0892281774
The bottom line teaching of this book focuses on how the Word of God is our weapon against every weapon the enemy has.