Background

Most individuals exposed to a traumatic event do not develop post-traumatic stress disorder (PTSD), although many individuals may experience sub-clinical levels of post-traumatic stress symptoms (PTSS). There are notable individual differences in the presence and severity of PTSS among individuals who report seemingly comparable traumatic events. Individual differences in PTSS following exposure to traumatic events could be influenced by pre-trauma vulnerabilities for developing PTSS/PTSD.

Methods

Pre-trauma psychological, psychophysiological and personality variables were prospectively assessed for their predictive relationships with post-traumatic stress symptoms (PTSS). Police and firefighter trainees were tested at the start of their professional training (i.e., pre-trauma; n = 211) and again several months after exposure to a potentially traumatic event (i.e., post-trauma, n = 99). Pre-trauma assessments included diagnostic interviews, psychological and personality measures and two psychophysiological assessment procedures. The psychophysiological assessments measured psychophysiologic reactivity to loud tones and the acquisition and extinction of a conditioned fear response. Post-trauma assessment included a measure of psychophysiologic reactivity during recollection of the traumatic event using a script-driven imagery task.

Results

Logistic stepwise regression identified the combination of lower IQ, higher depression score and poorer extinction of forehead (corrugator) electromyogram responses as pre-trauma predictors of higher PTSS. The combination of lower IQ and increased skin conductance (SC) reactivity to loud tones were identified as pre-trauma predictors of higher post-trauma psychophysiologic reactivity during recollection of the traumatic event. A univariate relationship was also observed between pre-trauma heart rate (HR) reactivity to fear cues during conditioning and post-trauma psychophysiologic reactivity.

Conclusion

The current study contributes to a very limited literature reporting results from truly prospective examinations of pre-trauma physiologic, psychologic, and demographic predictors of PTSS. Findings that combinations of lower estimated IQ, greater depression symptoms, a larger differential corrugator EMG response during extinction and larger SC responses to loud tones significantly predicted higher PTSS suggests that the process(es) underlying these traits contribute to the pathogenesis of subjective and physiological PTSS. Due to the low levels of PTSS severity and relatively restricted ranges of outcome scores due to the healthy nature of the participants, results may underestimate actual predictive relationships.

In the immediate aftermath of a traumatic event, many individuals experience physiological reactivity in response to reminders of the traumatic event that typically lessens over time. However, an overreliance on avoidant coping strategies may interfere with the natural recovery process, particularly for those who are highly reactive to trauma reminders. In the current investigation, we examined avoidant coping as a moderator of the association between heart rate reactivity to a trauma monologue measured shortly after a traumatic event and severity of posttraumatic stress disorder (PTSD) symptoms measured several months later. Fifty-five female survivors of assault completed PTSD diagnostic interviews and a self-report coping measure and participated in a trauma monologue procedure that included continuous heart rate measurement. These procedures were completed within 1 month of the assault and again 3 months postassault. After we controlled for the effect of initial symptom levels, the interaction of heart rate reactivity to the trauma monologue and avoidant coping measured at Time 1 was associated with PTSD symptom severity at Time 2. Individuals who are relatively highly reliant on avoidant coping strategies and relatively highly reactive to trauma reminders may be at greatest risk of maintaining or potentially increasing their PTSD symptoms within the first few months following the trauma. These findings may help inform early intervention efforts for survivors of traumatic events.

Studies have assessed relationships between posttraumatic stress disorder (PTSD) symptoms and physiological reactivity concurrently; fewer have assessed these relationships longitudinally. This study tests concurrent and prospective relationships between physiological reactivity (heart rate and skin conductance) to a monologue procedure and PTSD symptoms in female assault survivors, tested within 1 and 3 months posttrauma. After controlling for initial PTSD and peritraumatic dissociation, 3 measures of increased physiological reactivity to the trauma monologue at 1 month predicted 3-month PTSD reexperiencing severity. Additionally, increased heart rate following trauma and neutral monologues at 1 month was predictive of 3-month numbing symptoms. Implications for the prospective relationship between physiological reactivity to trauma cues and PTSD over time are discussed.

Researchers examining skin conductance (SC) as a measure of aversive conditioning commonly separate the SC response into two components when the CS-UCS interval is sufficiently long. This convention drew from early theorists who described these components, the first- and second-interval responses, as measuring orienting and conditional responses, respectively. The present report critically examines this scoring method through a literature review and a secondary data analysis of a large-scale study of police and firefighter trainees that used a differential aversive conditioning procedure (n = 287). The task included habituation, acquisition, and extinction phases, with colored circles as the CSs and shocks as the UCS. Results do not support the convention of separating the SC response into first- and second-interval responses. It is recommended that SC response scores be derived from data obtained across the entire CS-UCS interval.

The personality domain of introversion-extraversion has been theorized to be associated with the strength of fear conditioning, but the literature on this topic has been equivocal. Furthermore, except for extraversion and neuroticism, relationships of the other Big Five personality domains with fear response acquisition have not been explored. In the current study, multi-level modeling was used to examine the relationships of facets of the Big 5 domains to fear response acquisition. Participants were 217 police and firefighter trainees who completed the Revised NEO Personality Inventory (NEO-PI-R; Costa & McCrae, 1992) and a fear conditioning task as part of a larger study. Results indicated that several facets of extraversion have opposing associations with fear response acquisition of an electrodermal response– possibly contributing to the mixed results in the literature. Additionally, facets of other Big Five domains were found to be associated with fear response acquisition.