Factor structure of posttraumatic stress among Western New York undergraduates following the September 11th terrorist attack on the World Trade Center.

The structure of posttraumatic stress is of both theoretical and clinical interest. In the present study, seven models of posttraumatic stress were compared using confirmatory factor analysis. A sample of 528 Western New York undergraduate students was assessed 1 and 3 months after the September 11th, 2001 terrorist attacks. At the Month 1 assessment, the current three-factor Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; American Psychiatric Association, 1994) model, which consists of Intrusions, Avoidance/Numbing, and Hyperarousal, did not provide a good fit to the data; however, a four-factor model consisting of factors labeled Intrusions, Avoidance, Dysphoria, and Hyperarousal did fit the data well and provided better fit than the three-factor model and other competing models. Importantly, Dysphoria spans symptoms from the traditional DSM Numbing and Hyperarousal clusters. The four-factor model continued to fit the data well at Month 3. These findings parallel the results of earlier studies which suggest that a four-factor model better reflects the nature of posttraumatic stress than do simpler models, including the DSM. The present work is consistent with a dimensional model of stress responses and calls for further longitudinal work in this area.