Prior clinical (Behar, 1987; Kofoed et al., 1993; Saladin et al., 1995; Riggs et al., 2003; Evren et al., 2011) and epidemiological studies (Chilcoat and Menard, 2003; Grant et al., 2008; Kessler et al., 1997a,b) have consistently documented a strong association between PTSD and alcohol use disorders. Clinical studies have found that among individuals with PTSD, heavy alcohol drinking is associated with greater number (Behar, 1987) and more severe PTSD symptoms (Saladin et al., 1995), and prolonged course of illness (Herman, 1992; Yehuda et al., 1995). In addition, individuals with comorbid PTSD and alcohol dependence (AD) have higher prevalence of childhood trauma (Evren et al., 2011), earlier onset of AD symptoms (Driessen et al., 2008), poorer socioeconomic status (Riggs et al., 2003), and poorer physical and mental health (Evren et al., 2011), compared with those with AD only and their increased alcohol use is positively correlated with PTSD symptom severity (Bremner et al., 1996). Recent studies in clinical samples have suggested a reciprocal relationship between alcohol use and PTSD symptom improvement (Back et al., 2006), and trauma-focused exposure therapy significantly improved the symptoms of AD (Coffey et al., 2006).
