I attended a lecture today about addiction where the lecturer claimed that the American Medical Association requires that a phenomenon meet the following criteria to be considered a disease:

1) It must be progressive

2) It must manifest identifiable symptoms

3) It must occur chronically in affected individuals

4) It must be fatal if left untreated

That makes some things obvious diseases. Cancers, for example. There are many things that we consider diseases that do not fit these criteria, though. I believe that obesity, for example, is not officially considered a disease because it is not fatal. It’s correlated with many fatal conditions but isn’t fatal on its own. Most mental disorders fail to meet this criteria too. Anorexia is fatal if untreated, but anxiety disorders, dissociative disorders, ADHD, learning disorders, conduct disorders, psychotic disorders, and dissociative disorders and many others are not. There is a pretty good case to make for  alcoholism and some other addictions meeting these criteria. Disorders that are associated with suicidality, too, might qualify, like severe depression, and possibly “gender identity disorder,” though GID may not be progressive and so fail the first criteria.