(PS13-74) A Network Analysis of Posttraumatic Stress and Psychiatric Symptoms in Veterans with Comorbid PTSD and SMI

Introduction: The interactive model of trauma, posttraumatic stress disorder (PTSD), and severe mental illness (SMI) suggests that PTSD mediates the relationship between trauma exposure and psychiatric symptom severity (Mueser et al., 2002). Despite high rates of diagnostic comorbidity between PTSD and SMI, research has yet to elucidate the mechanisms of such as proposed by the interactive model. Notably, p</span>sychiatric comorbidity is often confounded by diagnostic errors prevalent in the medical model of mental disorders (Neale & Kindler, 1995). Network theory (Borsboom & Cramer, 2013; Cramer et al., 2010) circumvents this issue through granular analysis of construct interrelationships to identify bridge symptoms between latent factors. The current study used network theory to analyze the relationship between posttraumatic stress symptoms (PTSS) and SMI symptoms in a sample of Veterans with PTSD and comorbid SMI to explicate key mechanisms of Mueser et al.’s interactive model.  

Method: Participants were recruited from a PTSD specialty clinic in the southeastern United States as part of a separate clinical trial. The sample included 126 Veterans (75.4% Male; 50.8% Black, 42.9% White), ages 22-74 (Mage = 46.4 years; SD = 12.6) who presented with PTSD and co-occurring SMI. PTSD symptoms were assessed with the PTSD Checklist (PCL; Weathers et al., 1993), and psychiatric symptoms were assessed with the Brief Psychiatric Rating Scale – Expanded (BPRS-E; Lukoff et al., 1986; Thomas et al., 2004). The analyzed network was comprised of PCL symptom clusters (i.e., reexperiencing, avoidance, and hyperarousal) and the consensus four factors (i.e., positive symptoms, negative symptoms, affect, and activation) of the BPRS-E. SPSS 28.0 was used for analysis of clinical and demographic data. To account for differences in ranges, variables were standardized. R was used to conduct network analyses using the bootnet (Epskamp et al., 2018) and qgraph (Epskamp et al., 2012) packages. 

Results: With respect to PTSS, hyperarousal symptoms were strongly connected to both reexperiencing and avoidance symptoms. Reexperiencing symptoms were not connected to avoidance symptoms, indicative of mediation of the relationship by hyperarousal symptoms. Within the larger network, avoidance symptoms exhibited a strong, positive association with negative symptoms; activation symptoms were strongly connected to hyperarousal symptoms; and a strong, negative relationship was observed between activation and negative symptoms. One-step expected influence metrics indicated that hyperarousal symptoms had the highest expected influence. Avoidance symptoms were the second most central node.  

Discussion: Results from the current study inform understanding of the interactive model of trauma, PTSD, and SMI (Mueser et al., 2002). Specifically, both hyperarousal and avoidance symptoms were most central to the network between PTSS and SMI symptoms, with strong positive connections to activation and avoidance, respectively. Hyperarousal symptoms appear to be the primary maintenance mechanism for the PTSS network. Secondary results, as well as theoretical and clinical implications, will be discussed.