If he thinks it's only a spiritual issue, I would recommend this for him :http://www.amazon.com/Steps-Freedom-Christ-Study-Guide/dp/0764213733/ref=sr_1_1?ie=UTF8&qid=1416096973&sr=8-1&keywords=steps+to+freedom+in+christ+neil+anderson
For me, it was a first step in dealing with depression. Then, the other things have followed - diet, exercise, counseling, medications...