Evaluating a novel 8-factor dimensional model of PTSD in U.S. military veterans: Results from the National Health and Resilience in Veterans Study

Background: Accumulating data suggest that the symptom structure of posttraumatic stress disorder (PTSD) may be more nuanced than proposed by prevailing nosological models. Emerging theory further suggests that an 8-factor model with separate internally- (e.g., flashbacks) and externally- (e.g., trauma cue-related emotional reactivity) generated intrusive symptoms may best represent PTSD symptoms. To date, however, scarce research has evaluated the fit of this model and whether index traumas are differentially associated with it in populations at high risk for trauma exposure, such as military veterans. Methods: Data were analyzed from a nationally representative sample of 3,847 trauma-exposed U.S. military veterans who participated in the National Health and Resilience in Veterans Study. Confirmatory factor analyses were conducted to evaluate PTSD symptom structure. Results: The 8-factor model fit the data significantly better than the 7-factor hybrid and 4-factor DSM-5 models. Combat exposure and harming others were more strongly associated with internally-generated intrusions, while interpersonal violence and disaster/accident showed stronger significant associations with externally-generated intrusions.Limitations: The 8-factor model requires validation in non-veteran and more diverse populations, as well as with clinician-administered interviews. Conclusions: Findings support an 8-factor model of PTSD symptoms that separates out internally- and externally-generated intrusions. They also provide preliminary evidence that certain index traumas may lead to differential expression of these intrusive symptoms. Results support that PTSD symptoms may be better characterized by a more nuanced phenotypic structure, which is differentially linked to index traumas.