Traumatic events are common, with 50–70% of individuals experiencing at least one trauma in their lifetimes (Benjet et al., 2016). Posttraumatic Stress Disorder (PTSD), the signature trauma-related disorder (Breslau, 2009), is associated with increased alcohol consumption (Vlahov et al., 2002) and alcohol use disorder (AUD) (Jakupcak et al., 2010). Twin studies (Heath, Jardine, & Martin, 1989; Kaprio et al., 1987; Knopik et al., 2004; Stein et al., 2002) and genome-wide association studies (GWAS) (Clarke et al., 2017; Stein et al., 2016) find that PTSD and these alcohol phenotypes are moderately heritable, with 36–60% of the variance explained by genetic effects. Additional work using twin studies has demonstrated 30% genetic overlap between PTSD and AUD (McLeod et al., 2001; Xian et al., 2000). In general, most of the comorbidity research has focused on PTSD-AUD, and has neglected the association between PTSD-alcohol consumption. As increased alcohol consumption is associated with AUD (Moos, Schutte, Brennan, & Moos, 2004; Sanchez-Roige et al., 2019b), genetic research is needed to test whether the same genetic influences underlying PTSD-AUD are those underlying PTSD and alcohol consumption.
