Johns Hopkins Neuroscience Professor David Lynden wrote a book on the neurochemistry of pleasure and addiction titled The Compass of Pleasure. You can hear an amazing interview with him by going to (yikes!) NPR.org and typing the book title in the search box. He is very knowledgeable about addiction and had some amazing things to say. Some things we already know, like the brain is (sigh) permanently changed by addiction, and why stress triggers acting out. I found what he had to say very helpful in understanding what we're dealing with.