Baseline dissociation and prospective success in special forces assessment and selection

Although dissociation at the time of trauma (peritraumatic dissociation) has been shown to predict the development of posttraumatic stress disorder (PTSD), it is not yet known whether the tendency to dissociate under nonstressful circumstances (i.e., at baseline) can also serve as a predictor of vulnerability to stress in healthy individuals.

Baseline symptoms of dissociation (CADSS) were assessed in 774 active duty male soldiers enrolled in Special Forces Assessment and Selection (SFAS).

Soldiers who endorsed experiencing any symptoms of dissociation at baseline were significantly less likely to be successful in SFAS. The greater the number of symptoms of dissociation endorsed at baseline, the greater the likelihood of failure.

These data explain our earlier findings of fewer symptoms of dissociation in elite troops and may have relevance for the selection and hiring of personnel for nonmilitary, at-risk professions. Better screening may status (positively or negatively) in SFAS. Of the 794 SFAS candidates who were given the study recruitment speech, 774 candidates enrolled in the study. Thus, the refusal rate was three percent. Information on the 20 individuals who refused to participate in the study was not available to the research team.

Of the 794 candidates approached, 774 (97%) active duty male soldiers (mean age 26, SD=4) agreed to participate in the study. All participants were enrolled in a US Army SFAS program. The participants' mean years of service in the Army was 4.9 (SD=3.2). Two-hundred eighty soldiers (36%) were married, 403 (52%) soldiers were single, and 86 (11%) soldiers were divorced. Eighty-six percent or 677 candidates were enlisted and 110 (14%) were officers.

After providing informed consent, participants completed the self-report portion of the Clinician Administered Dissociative Symptom Scale (CADSS). The CADSS is a reliable, valid, self-report instrument designed to assess state symptoms of dissociation in response to a specified stressor.(14) Subjects were instructed to complete the CADSS using the week previous to enrollment in the course as their reference point. Subjects were instructed to inform the research team (orally and in writing) if during the previous week they had experienced any traumatic or highly stressful events. We did not include the clinician-observer component of the CADSS given the low intercorrelation coefficients for this component. After completing the CADSS, participants commenced participation in SFAS.

In order to test the hypothesis that symptoms of dissociation would be significantly related to success or failure in SFAS, the following variables were created: total CADSS scores (the sum of individual CADSS items); classification scores indicating whether or not subjects reported symptoms of dissociation at baseline (1=yes; 0=no); and two additional classification scores designed to classify subjects in a binary fashion based on whether or not their CADSS total score was greater than, at, or below a specified value (less than 5; equal to, or greater than, 5; less than 11; equal to or greater than 11). These classification cut-off points were selected based on the distribution of responses from subjects in this study and on the mean pre-stress CADSS dissociation scores noted in our previous studies.(15) Chi-squared analyses were performed to test whether subjects endorsing baseline symptoms of dissociation (any, greater than 5 points, greater than 11 points) were more likely to fail SFAS compared to peers who did not report such symptoms. Receiver operator characteristics (ROC) curvesROC curves were created by using the CADSS baseline total score (the test variable) in order to predict outcome in the SFAS program (the state variable, where 1= failed SFAS). ROC graphs were created for the group as a whole and for the sub-group of subjects whose CADSS score was 1 or greater. For both ROC graphs, the area under the curve as well as coordinate points for the curve were calculated (SPSS 11.5). The null hypothesis assumption was that the true area under the curve equals 0.5. With regard to the parameters for the standard distribution of error, the distribution assumption was nonparametric and the confidence interval 95 percent.(16) Although this method is also a regression model, it offers an advantage over the logistic regression format in that a classification table corresponding to specific scores on the CADSS and to the likelihood of success or failure in the course is possible.