There have been many attempts to classify alcoholics into more clinically homogeneous groups, for example in terms of age of onset, predisposing personalities, psychiatric comorbidity, severity of disease and withdrawal symptoms [1,12]. Etiological factors, including genetic influences, might be shared within each group. An empirical classification based on a factor analysis of NESARC data from nearly 1500 alcoholics identified five homogeneous subtypes: (a) young adult (32%), (b) functional (19%), (c) intermediate familial (19%), (d) young antisocial (21%) and (e) chronic severe (9%). These subtypes were distinguishable by family history of alcoholism, age of AUD onset, rates of antisocial personality disorder (ASPD), endorsement of specific DSM-IV AUD criteria, and comorbid mood, anxiety and substance use disorders [13]. The five subgroups had different clinical outcomes three years later [14]. This empirical classification of alcoholics in the general US population suggests that the groups might differ in genetic vulnerability to AUD which might have implications for pharmacogenetic approaches to treatment. Moreover, this empirical classification is relevant to the recruitment of alcoholics for research studies in order to reduce phenotype heterogeneity.
