Posttraumatic stress disorder (PTSD) is associated with increased risk for substance use disorders (SUDs; Najavits, Weiss,&Shaw, 1997). Studies have found rates of PTSD and SUD comorbidity as high as 25-59% (Brown, Recupero,&Stout, 1995; Najavits, et al., 1997; Stewart et al., 2000). Read, Brown and Kahler (2004) found that having PTSD and increased psychiatric distress associated with comorbid disorders was associated with poorer substance use outcomes. Additionally, Ritsher et al. (2002) found that dually diagnosed patients were not only less likely to be in remission when compared to an SUD-only group, but that they did have more severe levels of distress. However, other studies suggest that there are no significant differences for treatment outcomes between those with comorbid PTSD and SUD, and SUD-only groups (e.g., Norman, Tate, Anderson,&Brown, 2007). Several theorists believe that using substances for extended periods of time may be a causal factor in mental health symptomatology, or that it exacerbates existing psychiatric symptoms (e.g. Blume, Schmaling,&Marlatt, 2000; Miller, Eriksen,&Owley, 1994). Alternatively, self-medication theorists assert that individuals use substances as a coping mechanism for negative emotions (Khantzian, 1997). Ouimette et al. (2007) found that patients with PTSD reported that their substance abuse relapse was in response to depression more often than people without PTSD. Meanwhile, Waldrop, Back, Verduin, and Brady (2007) proposed that alcohol may have dampening effects that help regulate the anxiety of patients with PTSD and that cocaine may increase hypervigilance and self-confidence to help individuals with PTSD feel more in control in social situations. There is some evidence for both theoretical points of view. For example, Gil-Rivas, Prause, and Grella (2009) found that individuals with co-occurring disorders reported that they experienced depressive and anxiety symptoms before relapse, which supports the self-medication theory. However, these individuals reported that those symptoms did not diminish, and in fact, were exacerbated after drug use.
