Four categories of lifetime psychopathology were considered in this analysis: 1) neither internalizing nor externalizing (NINE); 2) internalizing only (IO); 3) externalizing only (EO); and 4) both internalizing and externalizing (BIE). This categorization corresponds to one of the most strongly validated alcohol typologies considered in a study by Penick et al.(1999). In this study, internalizing psychopathology comprised lifetime major depression, bipolar I and II disorders, dysthymia, panic disorder with or without agoraphobia, specific or social phobia and generalized anxiety disorder. Externalizing psychopathology comprised antisocial personality disorder (ASPD) and lifetime illicit drug dependence.
