There is an extensive literature supporting the relationship of externalizing disorders to subsequent development of AUDs and this has formed the basis of certain typologies of AUD, including Types 1 and 2 ([20] Cloninger, 1987) and Types A and B ([21] Babor et al., 1992). Type 2 subjects are characterized by high novelty seeking, low harm avoidance, and low reward dependence ([20] Cloninger, 1987). They are more likely to be diagnosed with antisocial personality disorder and less likely to be able to abstain from alcohol. Type B subjects are more likely to have a history of childhood aggression and conduct disorder and less likely to have a sustained response to treatment in comparison to Type A subjects ([21] Babor et al., 1992). More recent studies also emphasize the role of externalizing disorders, such as conduct disorder and attention deficit hyperactivity disorder in increasing the risk for alcohol problems ([22] Kuperman et al., 2001; [23] Bucholz et al., 2017; [24] Groenman et al., 2017). Cannabis and tobacco use are also associated with increased risk for concomitant alcohol problems ([23] Bucholz et al., 2017).
