Conceptualizing comorbid PTSD and depression among treatment-seeking, active duty military service members

Background: Among active duty service members and veterans with PTSD, depression is the most commonly diagnosed comorbid psychiatric condition. More research is warranted to investigate the relationship between PTSD and depression to improve treatment approaches. Byllesby et al. (2017) used confirmatory factor analyses in a sample of trauma-exposed combat veterans with PTSD and found that only the general distress factor, and not any specific symptom cluster of PTSD, predicted depression. This study seeks to replicate Byllesby et al. (2017) in a sample of treatment-seeking active duty soldiers. Methods: Confirmatory factor analyses, bifactor modeling, and structural equation modeling (SEM) were used with data gathered at pretreatment and posttreatment as part of a large randomized clinical trial. Results: Confirmatory factor analyses and bifactor modeling demonstrated that PTSD symptom clusters, Negative Alterations in Cognition and Mood (NACM) and Alterations in Arousal and Reactivity (AAR), as well as the general distress factor significantly predicted depression at pretreatment and posttreatment. Limitations: The current study was predominantly male, limiting the generalizability to female service members with PTSD. Also, self-report measures were used, which may introduce response-bias. Conclusions: The current study did not replicate Byllesby et al. (2017). Results demonstrated that the relationship between PTSD and depression among active duty service members can be explained by both transdiagnostic factors and disorder-specific symptoms.