Comparing posttraumatic stress disorder's symptom structure between deployed and nondeployed veterans.

We tested two empirically validated 4-factor models of posttraumatic stress disorder (PTSD) symptoms using the PTSD Checklist: King, Leskin, King, and Weathers' (1998) model including reexperiencing, avoidance, emotional numbing, and hyperarousal factors, and Simms, Watson, and Doebbeling's (2002) model including reexperiencing, avoidance, dysphoria, and hyperarousal. Our aim was to determine which fit better in two groups of military veterans: peacekeepers previously deployed to a war zone (deployed group) and those trained for peacekeeping operations who were not deployed (nondeployed group). We compared the groups using multigroup confirmatory factor analysis. Adequate model fit was demonstrated among the nondeployed group, with no significant difference between King et al.'s (1998) model (separating avoidance and numbing) and Simms et al.'s (2002) similar model involving a dysphoria factor. A better fitting factor structure consistent with Simms et al.'s (2002) model was found in the deployed group. Comprehensive measurement invariance testing demonstrated significant differences between the deployed and nondeployed groups on all structural parameters, except observed variable intercepts (thus indicating similarities only in PTSD item severity). These findings add to researchers' understanding of PTSD's factor structure, given the revision of PTSD that will appear in the forthcoming 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 2010)--namely, that the factor structure may be quite different between groups with and without exposure to major traumatic events.

Assessing posttraumatic stress disorder with or without reference to a single, worst traumatic event: examining differences in factor structure.

The authors examined the effects of a methodological manipulation on the Posttraumatic Stress Disorder (PTSD) Checklist's factor structure: specifically, whether respondents were instructed to reference a single worst traumatic event when rating PTSD symptoms. Nonclinical, trauma-exposed participants were randomly assigned to 1 of 2 PTSD assessment conditions: referencing PTSD symptoms to their worst trauma (trauma-specific group, n = 218) or to their overall trauma history in general (trauma-general group, n = 234). A 3rd group of non-trauma-exposed participants (n = 464) rated PTSD symptoms globally from any stressful event. Using confirmatory factor analysis, the authors show that the 4-factor PTSD model proposed by D. W. King, G. A. Leskin, L. A. King, and F. W. Weathers (1998; separating effortful avoidance and emotional numbing) demonstrated the best model fit for trauma-general and non-trauma-exposed participants. The 4-factor PTSD model proposed by L. J. Simms, D. Watson, and B. N. Doebbeling (2002; emphasizing a general dysphoria factor) demonstrated the best model fit for trauma-specific participants. Measurement invariance testing revealed that non-trauma-exposed participants were different from both trauma-exposed groups on factor structure parameters, but trauma groups were not substantially different from each other.

Tobacco use and body mass index: mediated effects through physical inactivity.

The current study examined associations between smoking and body mass index (BMI) utilizing a nationally representative sample of adults (N = 1547). Previous research has shown that smokers have lower BMI than non-smokers; however among smokers, tobacco use is positively associated with BMI. Previous authors have hypothesized this is due to poor behavioral habits among smokers. Building on this, we found that smoking was positively associated with physical inactivity, which mediated the association between tobacco use and BMI. Interpretation, limitations, and future directions are discussed.