The structure of posttraumatic stress symptoms.

Abstract

Posttraumatic stress disorder, as defined by the Diagnostic and Statistical Manual of Mental Disorders (3rd ed., rev. and 4th ed.; American Psychiatric Association, 1987, 1994, respectively), is characterized by 17 symptoms, descriptively clustered into 3 groups: (a) intrusions, (b) hyperarousal, and (c) avoidance and numbing. The present study sought to identify the basic dimensions (factors) that underlie these symptoms. Two samples were assessed: 103 victims of motor vehicle accidents and 419 United Nations peacekeepers deployed in Bosnia. A principal axis factor analysis was conducted for each sample. In each sample, 2 correlated factors were obtained, which were very similar across samples. Factor 1 was labeled Intrusions and Avoidance, and Factor 2 represented Hyperarousal and Numbing. These factors loaded on a single higher order factor. The higher order factor accounted for 13% to 38% of variance in symptom severity, and the lower order factors accounted for an additional 8% to 9% of variance. If the authors assume that each factor corresponds to a distinct mechanism (R. B. Cattell, 1978), then the results suggest that posttraumatic stress reactions arise from a general mechanism, with contributions from 2 specific mechanisms.

Prediction of numbing and effortful avoidance in female rape survivors with chronic PTSD

“…Fewer studies of the factor structure of PTSD have assessed civilian samples. Among them are one of the most rigorous factor-analytic studies to date (Taylor et al, 1998) and a replication of this study (Buckley, Blanchard, & Hickling, 1998), which both support a two-factor model of PTSD.…”

“…Fewer studies of the factor structure of PTSD have assessed civilian samples. Among them are one of the most rigorous factor-analytic studies to date (Taylor et al, 1998) and a replication of this study (Buckley, Blanchard, & Hickling, 1998), which both support a two-factor model of PTSD.The Taylor and colleagues (1998) empirical study focused on the 17 symptom criteria of the current PTSD diagnosis in samples of motor vehicle accident victims and United Nations peacekeepers. The results suggest an alternative symptom configuration that may more accurately reflect the factor structure of PTSD in civilian populations than does the current DSM-IV configuration.…”

“…However, as the CAPS interview was used to assess all symptoms of PTSD, it is important to note the possible role of shared method variance in the correlations between clusters. The patterns revealed in the regression analyses do seem to support the more specific hypothesis that numbing/arousal and avoidance/intrusion may be related mechanisms within PTSD (Foa et al, 1992;Litz et al, 1997;Taylor et al, 1998). Equally importantly, the power analyses for testing the null hypotheses suggest that numbing/intrusion, and avoidance/arousal are not significantly related to each other.…”

“…In the DSM-IV (APA, 1994) the diagnostic category includes three clusters: reexperiencing, avoidance, and arousal. In recent years there has been some debate over whether or not these clusters accurately represent the dimensions underlying the disorder (Foa, Riggs, & Gershuny, 1995;Litz et al, 1997;Taylor, Koch, Kuch, Crockett, & Passey, 1998). Previous studies of the structure of PTSD have generally focused on veteran populations.…”

Factorial invariance of posttraumatic stress disorder symptoms across three veteran samples

“…The present study was designed to first test the model fit of the conventional 3-factor structure of PTSD symptoms compared to five alternative theoretical models that have received empirical support in prior studies (seeTable 1) including the two 4-factor models reviewed above (King et al, 1998;Simms et al, 2002), two 2-factor models (Maes et al, 1998;Taylor, Kuch, Koch,Crockett,&Passey, 1998), and a unifactorial model that regards PTSD a unitary construct. First, each of the six models was statistically compared for each veteran cohort.…”