Akin to how any perceived deviation may “serve” to turn an individual into a pharmakos, an outcast, any behavioral deviation may in principle serve as a basis of elevated liability to addiction. A relatively small deviation in childhood or adolescence, due to passive, evocative and then active phenotype (and genotype)–environment correlations (Scarr and McCartney, 1983) compounding its effect, may snowball to full-blown antisociality, with drug abuse and subsequent addiction as its attributes. It may be expressed in the need to self-medicate against depression, corresponding to the internalizing deviation, or to correct for an externalizing deviation, including a subjectively or objectively low amplitude of sensations, boredom, underarousal, wherein lies a possible connection with psychopathy (overlapping with antisociality). More than 50% of addicts have other psychopathology (Regier et al., 1990), and they are at particularly high risk of having comorbid externalizing disorder (Compton et al., 2005; Kessler et al., 2001; Warner et al., 1995). In genetically informative data, SUD clusters with externalizing rather than internalizing behavior disorders (Kendler et al., 2007). This pertains to genetic connections (correlations) as well, and gives grounds
