Megan Cardenas, B.S., Warriors Research Institute, Baylor Scott & White Health; Jordan Smith, MPH, Warriors Research Institute, Baylor Scott & White Health; Michelle Pennington, MPH, Warriors Research Institute, Baylor Scott & White Health; Elizabeth Coe, PsyD, Warriors Research Institute, Baylor Scott & White Health; Tom Carpenter, PhD, Seattle Pacific University; Eric C. Meyer, PhD, University of Pittsburgh; Rose Zimering, PhD, Boston University School of Medicine, Veterans Affairs Boston Healthcare System; Suzy B. Gulliver, PhD, Warriors Research Institute, Baylor Scott & White Health, Texas A&M Health Science Center

Purpose/Objectives
The aim of this study was to assess individual tendencies towards thought suppression and their relationship to post-traumatic stress disorder (PTSD) symptom severity. We hypothesized that firefighters who demonstrated higher levels of thought suppression would report greater levels of PTSD symptom severity, independent of their trauma exposure history.

Background
Due to the nature of their profession, firefighters are routinely exposed to traumatic events, putting them at an increased risk for developing psychological and behavioral health problems. Previous research has demonstrated elevated rates of PTSD among firefighters with prevalence rates ranging from 6 to 30%. A hallmark of PTSD is the recurrence of distressing intrusive thoughts, which individuals may be inclined to suppress in order to cope. Paradoxically, research has shown that thought suppression is linked to an increase in the unwanted thoughts. Mental health outcomes of trauma-exposed populations have also been shown to be greatly impacted by the use of thought suppression. In studies of trauma-exposed populations with a PTSD diagnosis, thought suppression has been shown to be a significant predictor of psychopathology and a key contributor to increases in PTSD symptom severity. It is possible that similar results could be found in firefighters who experience similarly significant exposure to potentially traumatic events (PTEs).

Methods
This study was a secondary data analysis of data gathered from a larger study, which followed 322 firefighters through their first three years of fire service. Firefighters at baseline (n=313) and the first (n=205), second (n=175), and third (n=170) annual follow-ups completed a variety of measures to assess psychological wellbeing. Levels of thought suppression were measured using the 15-item White Bear Suppression Inventory (WBSI), and PTSD symptoms were measured using the 17-item PTSD Checklist – Civilian Version (PCL-C). Trauma exposure history was measured by summing two measures of PTEs experienced on and off the job. The Firefighter Work Experience Questionnaire (FFWE) assessed the number of PTEs incurred in the line of duty as a firefighter, and the Trauma History Questionnaire (THQ) assessed lifetime PTEs experienced off the job. The THQ was administered at baseline, year one, year two, and year three, and the FFWE was administered at year one, year two, and year three.

Findings
We examined the degree to which a tendency toward thought suppression would predict individual differences in PTSD symptoms, controlling for trauma exposure. Data were drawn from responses to the WBSI, PCL-C, THQ, and FFWE administered at baseline, year one, year two, and year three. Data were analyzed with structural equation modeling. Trait-level factors for thought suppression and PTSD were estimated. We observed a large link between a tendency to report thought suppression and a tendency to experience PTSD symptoms, regardless of trauma symptoms. Without controlling for trauma exposure, trait thought suppression correlated with PTSD symptoms at ϕ =.91, p < .001. In a model controlling for trauma exposure, this remained large at b = .81, p < .001.

Discussion
These results support our hypothesis that higher degrees of thought suppression are predictive of increased PTSD symptom severity at the individual level, even when controlling for trauma exposure history. The increases in psychopathology with higher levels of thought suppression are consistent with the existing research in other trauma-exposed populations. These findings are also consistent with the concept of thought suppression as a maintaining factor of PTSD, which would support the design of interventions to teach individuals with PTSD alternative emotion regulation strategies to avoid the perpetuation of thought suppression tendencies.

One limitation of this work may be the use of the WBSI total score as some prior research suggests the questionnaire measures not only levels of thought suppression but also the experience of intrusive thoughts; thus, future work may benefit from implementing subscores of the WBSI into their analyses. Our study was also limited by the aggregate scoring used for analysis as patterns from year to year were not able to be assessed.

Conclusions
These results emphasize the importance of considering an individual’s tendency towards thought suppression as a complicating factor of PTSD severity in firefighters, a population vulnerable to mental health disorders. Further research should examine the relationship between thought suppression and other psychological symptoms as it relates to firefighters and other populations routinely exposed to traumatic events, as well as the effects of psychological treatment on individual tendency towards thought suppression.

Tags: Basic research, Public safety, Secondary or archival analysis, Traumatic Stress and Resilience, Workplace Stress; Outcomes; and Recovery