Posttraumatic stress disorder in a therapeutic community for substance use disorders: an evaluation of the influence

The purpose of this body of research is twofold. First, to investigate posttraumatic stress disorder (PTSD) in a sample of adults undergoing substance use disorder (SUD) treatment in a therapeutic community (TC) and, second, to apply major psychological theories to help understand the nature of this comorbidity in ways that inform treatment. The focal theories of this research are: emotion dysregulation (Gratz & Roemer, 2004), and revised Reinforcement Sensitivity Theory (rRST; Corr, 2008; Gray & McNaughton, 2000). Rash Impulsiveness (Dawe & Loxton, 2004) will be included as an important dimension of rRST that has been consistently linked to substance misuse. Chapter 1 presents an overview of research related to the thesis as a whole. In Chapter Two, a systematic review of TC literature reveals that PTSD is under-researched in the TC context, despite a high prevalence of individuals with PTSD - SUD comorbidity. In order to establish the prevalence of PTSD in our TC sample, Chapter Three describes a psychometric validation of the Posttraumatic Stress Disorder Checklist - Civilian Version (PCL-C) in a sample of 120 adults undergoing treatment in a TC. The PCL-C was found to have good model fit (χ2 (114) = 216.340, p < . 001, RMSEA = . 087, CI . 069-. 104, CMIN/df = 1.898, CFI = . 923 and SRMR = . 0577), and high reliability, α = . 944, n = 120. In Chapter Four, the prevalence and process of change of posttraumatic stress symptoms (PTSS) during treatment, and 3 months following treatment, was investigated. A majority, 64%, of the sample met the Veteran's Affairs (VA) suggested PCL-C diagnostic threshold for PTSD at the start of rehabilitation. The severity of PTSS significantly influenced the length of stay in treatment (r = -.23, p < .01). Nevertheless, for those who stayed in treatment, PTSS significantly decreased during the course of treatment, t (21) = 3.17, p <. 01, d = . 67. In Chapter Five, correlational analyses revealed that PTSS was positively related to all six facets of the Difficulties in Emotion Regulation (DERS) scale reported at early treatment (r = .31 to .72, p < .00). Furthermore, the correlations between PTSS and two of the facets of rRST, BAS and fight-flight-freeze sensitivity (FFFS), were significantly correlated (r = -.23 and .49, p < .01, respectively). BAS sensitivity was shown to negatively correlate with PTSS, indicating that lower BAS sensitivity related to higher PTS severity. No relationship was found between the Behavioural Inhibition System (BIS) and PTSS. Finally, Rash Impulsivity significantly correlated with PTSS at intake, r = . 50, p < . 00. Contrary to hypotheses, and previous research, Rash Impulsivity did not significantly correlate with retention. Theoretical mechanisms linking PTSS and substance misuse were investigated further, with tests of theoretical models in which individual difference factors (facets of the rRST) were related to retention and outcomes from treatment, and facets of emotional dysregulation were tested as mediators of this relationship. Upon investigation through linear regression, no suitable variable was found the mediate the relationship between PTSS and retention. The final moderated mediated model, therefore, was not suitable for this population. Limited moderation, though, occurred between the two facets of rRST and retention. Specifically, investigation of the simple slopes showed that FFFS and Rash Impulsivity both moderate the relationship between PTSD and retention at high (+1 SD) and mean scores. These findings indicate that high levels of both facets do interact with PTSD to negatively influence treatment retention. The null findings for both mediation and the moderated mediation model contradict previous research, and may be due to homogeneity in scores across the population. Overall, some implications for treatment can be extrapolated. First, PTSD is highly prevalent in the TC population, and should be assessed using psychometrically valid measures, such as the PCL-C, and addressed in treatment. Second, treatment for SUD does not exacerbate PTSD; on the contrary, PTSS significantly decreased during TC treatment. Finally, as there is solid theoretical support to suggest an influence of emotion dysregulation and Rash Impulsiveness on retention and outcomes, more research needs to be conducted on the role of these two constructs with the intent of creating a better suited rehabilitation program for individuals with a PTSD - SUD comorbidity.