Most of the work on subtyping substance dependence disorders has focused on alcohol dependence. These efforts have produced several sub typing schemes (Hesselbrock & Hesselbrock 2006). The best known of these are Cloninger’s Types I and II (Cloninger et al. 1981) and Babor’s Types A and B (Babor et al. 1992; Brown et al. 1994). Cloninger’s Type II and Babor’s Type B are similar in having earlier onset of drinking problems, more antisocial and other psychiatric co-morbidity, a more severe course as opposed to Type I and Type A. A Type A/B dichotomy has been found for alcohol dependence in several ethnicities (Hesselbrock & Hesselbrock 2006). Evidence suggests that type II/B might be more heritable than type I/A (Cloninger et al. 1981; Foroud et al. 1998), raising the possibility that Type II/B is more genetically based and Type I/A more environmentally based (Hesselbrock & Hesselbrock 2006).
