Twin studies can be used to assess possible mechanisms underlying the childhood maltreatment–alcoholism association, and estimate the degree to which environmental and genetic factors contribute to individual differences in these outcomes and their overlap. Co-twin control analyses ascertain pairs discordant for childhood maltreatment and calculate alcoholism risk in the exposed twin compared with the unexposed co-twin control. This method statistically adjusts for family environmental and genetic factors and allows for the investigation of causal versus indirect interpretations. Available co-twin control studies provide evidence consistent with childhood sexual abuse as a direct risk factor for subsequent alcohol-related problems (Kendler et al. 2000; Nelson et al. 2002), but there is also evidence that the association may be partially mediated by family factors (Dinwiddie et al. 2000). Less is known about the mechanisms underlying the association between physical abuse or neglect and alcoholism. Additional population-based research is needed to clarify the role of childhood maltreatment in the development of alcoholism among males, and to better distinguish the effects of childhood maltreatment on alcoholism from confounded risk factors such as family environment.
