The genetic risk for alcohol dependence has in large part been linked to shared genetic risk for externalizing psychopathology, which is characterized by aggressive and impulsive personality traits and antisocial behavior (Kendler et al., 2003; Krueger et al., 2005). Alcohol dependence is, however, also highly co-morbid with internalizing disorders such as anxiety and depression, and an internalizing pathway to alcohol dependence involving negative affect has also been described (Hussong et al., 2011). These two pathways are not necessarily mutually exclusive. Neuroticism as a personality trait in general has a strong shared genetic component with internalizing disorders (Hettema et al., 2006), but also accounts for some of the comorbidity between internalizing and externalizing disorders, as well as comorbidity within externalizing disorders (Khan et al., 2005). In this context, our findings are consistent with the concept of an internalizing pathway to alcohol dependence. We found exposure to emotional abuse correlated with neuroticism, which in turn correlated with greater severity of alcohol dependence. This “negative affect” pathway is likely to involve mood-related drinking motives, i.e., drinking to cope with negative mood, which have been shown to mediate relationships between negative affect, major depression, and alcohol-related problems (Young-Wolff et al., 2009).
