Recently, efforts have been made to subtype drug use disorders using cluster analysis. Ball and colleagues (1995) adduced evidence for a Type A/B in cocaine abusers. Feingold and colleagues (1996) adduced evidence for a Type A/B dichotomy from a group of alcohol, cocaine, marijuana, and opiate abusers approximately 60% of whom were recruited from treatment programs. Kranzler and colleagues (2008), in a study of cocaine dependence in 1393 subjects from 660 small nuclear families, identified 6 clusters, four of which showed rates of cocaine dependence of 78–100% with heritability ranging from 0.32 to 0.50. In those 4 clusters, rates of ASPD ranged from 9.3 to 19.9% and major depression episode from 6.7 to 20.1%. Gelernter and colleagues (2006) used cluster analytic methods to identify three clusters of moderate to heavy opioid users with heritability ranging from 0.40 to 0.65. These studies are producing specific genome wide scan information (Gelernter et al. 2005, 2006).
