Thanks Sarah, that is a great question!  In my experience working with people who have an addictive disorder, I have yet to meet a client who did not have any underlying issues (regardless of the problematic substance/behaviour).  This includes sub-clinical issues and/or diagnosable conditions.  Even in cases where there were no severe underlying conditions, the addiction and it's subsequent consequences required attention and repair.  Frequently, once someone develops a habitual behaviour, they experience triggers and urges that are aided by learning coping skills and identifying relapse prevention strategies.  This may not be the case in situations when people have more mild or moderate problems but unfortunately, by the time many clients seek out professional services, their symptoms tend to be more severe.