Yes, it is adequate, but my advice to any write who is seriously considering writing about anything psychologically related is to simply buy a psychology book related to what you want. They, for the most part, are not that hard to understand and are very often much more interesting than any how-to book or any mass market fiction. This book gives a good overview, but not much else.
My advice is:
If you are writing about forensic psychology in general read: "Dark Dreams" by Roy Hazelwood and or "Mindhunter" by John Douglas as well as "On-Scene Guide for Crisis Negotiators" by Lanceley. These books will teach you more than any how to book ever could. They have been invaluable to me.
If you are writing about a specific disorder: Browse through the Diagnostic and Statistical Manual for Mental Disorders(DSM IV) if you don't know which disorder to use. After that, simply get a book about that specific disorder. Here are my reccomendations-
Dissociative identity Disorder (multiple personality)- "The Dissociative Identity Sourcebook", "Got Parts? An Insider's guide to Dissociative Identity disorder"
Post-Traumatic Stress- "Post Traumatic Stress Disorder- A Victim's Guide To Healing and Recovery"
Scizophrenia- "Schizophrenia Symptoms Causes and Treatments"; "Mad in America" (this is more a history of schizophrenia in American medicine, but it is AMAZING and eye-opening.)
Addiction- "The Addictive Personality" by Nakkan. (One of my personal favorites) or anything by Terance Gorski.
And of course, get a book specific to the addiction. Just look, you'll be surprised at what's available! And, also watch A&E's show "Intervention". Seeing actual addicts will really add to your characters.
Basically, just get a specific book on what you to do. It will be much more helpful than this, which is okay, but basically just an overview. Just do a little research. Nothing can substitute for the real thing. Don't be afraid to buckle down and do a little digging and hard work. It will pay off immensly and give your work an air of truth that an over view like this can't provide. Trust me, I'm speaking from experience. Come to think of it, after this I think I'll creat a list on Listmania. I'll call it... A writer's guide to the mind. It'll have much more on it!
*And of course, all of these items are avaliable on Amazon.