Brought up the critically important though commonly overlooked facts regarding comorbidities with addictionMuchas Gratias , The kind of radical way I look at dependence is that it ' s not really different from any other kind of dependence You need A to get B . If it ' s heroin , you need it to stay functional , if it ' s your car , you need it to transport yourself efficiently . I also don ' t believe modifiers like psychological or physical can really be used distinctly , because the brain and body are so intertwined any effect on one causes an immediate effect in the other . Thus , at best you ' d get mostly physically dependent for a car , since one can still walk , or mostly psychologically dependent for air conditioning , since we can still work just as well in somewhat uncomfortable temperatures , mainly it ' s contentment we lose . That ' s my view of the subject anyway . You talk about the phenomenon that addicts will chase a high after the drug ceases to provide it , one could extend this to binge eating the individual consumes more and more in a vain attempt to replicate that first high of satisfying hunger . Just a thought . As for what makes a disorder , I think this question is made far more complicated by the fact that disorder and abnormality are often falsely used as synonyms . For your shyness example , what is a disorder of shyness in one culture may be expected in another . As for you ' d have to ask an expert , I have , many many times , and I find one almost always gets the same canned , textbook reply and an obvious lack of conscious consideration . Doctors and the like are , unfortunately , barred from having real life experiences in these matters , meaning they usually cannot relate to the human aspect of it whatsoever . Imagine a musician who doesn ' t listen to music , a mechanic who has never driven . Clearly this causes problems . As for impulsivity , I tend to think we are all , at our core , impulsive creatures . Usually whether someone decides to try drugs or abstain , when asked , their answer is clearly very impulsive , if for different reasons . And the people who seem not to get hooked on things like heroin , I tend to see this not as due to a lack of impulsivity but a stronger sense of caution andor awareness of the potential negative effects .