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. Author manuscript; available in PMC: 2018 Mar 29.
Published in final edited form as: Psychol Trauma. 2016 Nov 21;9(4):479–484. doi: 10.1037/tra0000215

Association of Peritraumatic Dissociation With Symptoms of Depression and Posttraumatic Stress Disorder

Erin C McCanlies 1, Khachatur Sarkisian 2, Michael E Andrew 3, Cecil M Burchfiel 4, John M Violanti 5
PMCID: PMC5875421  NIHMSID: NIHMS953281  PMID: 27869465

Abstract

Aim

In this study, we evaluated whether peritraumatic dissociation (PD) was associated with symptoms of depression and posttraumatic stress disorder (PTSD), and whether this association was modified by trauma prior to police work.

Method

Symptoms of depression, PTSD, peritraumatic dissociative experience (PDE), and trauma prior to police work were measured using the Center for Epidemiologic Studies Depression scale, PTSD Checklist–Civilian, PDE questionnaire, and the Brief Trauma questionnaire, respectively, in 328 police officers. Separate regression models were used to assess if either symptoms of depression or PTSD were associated with PD stratified by prior trauma. Means were adjusted for race, number of drinks per week, and smoking.

Results

PD was associated with symptoms of PTSD and depression (β = 0.65, p < .001 and β = 0.27, p < .001, respectively). PD was positively associated with symptoms of PTSD regardless of prior trauma (β = 0.61, p < .001(without prior trauma), 0.75, p < .001 (with prior trauma). In contrast to PTSD, depression symptoms were significantly associated with PD scores in individuals with prior trauma (β = 0.47, p < .001), but not in individuals without prior trauma (β = 0.13, p = .165).

Limitations

This is a cross-sectional study. Outcomes were obtained via self-report and were not clinically diagnosed. Aspects of both the trauma event as well as the symptoms and severity of PD may have introduced recall bias.

Conclusion

These results add to the literature indicating that PD plays a role in symptoms of PTSD and depression and how prior trauma may modify this relationship.

Keywords: depression, PTSD, posttraumatic stress disorder, peritraumatic dissociation, prior trauma

Police officers have higher rates of posttraumatic stress disorder (PTSD) and depression than the general population (Carlier, Lamberts, & Gersons, 1997; Gersons, 1989; Robinson, Sigman, & Wilson, 1997). Although both peritraumatic dissociation (PD) and prior trauma are independently associated with PTSD and depression, prior trauma may modify the association between PD and PTSD or depression, further increasing the risk of these disorders in officers. Determining if prior trauma in police officers moderates the association between PD and PTSD or PD and depression, may also help to clarify the etiology of PTSD or depression in this high-risk population, furthering our understanding of who may be at the greatest risk.

PTSD and depression are serious psychological disorders that can occur following exposure to one or more traumatic events (Hodgson & Webster, 2011; Johnson, Pike, & Chard, 2001; Marmar, Weiss, Metzler, & Delucchi, 1996; Marmar et al., 1999). Police officers are repeatedly exposed to traumatic events across their working lives, including motor vehicle accidents, armed conflicts, and witnessing violent death (Marmar et al., 2006). For this reason, rates of PTSD and depression may be higher in police officers than in the general population (Carlier et al., 1997; Gersons, 1989; Robinson et al., 1997). Furthermore, police officers with PTSD or depression are at an increased risk for negative health issues such as cardiovascular disease and gastrointestinal disorders, comorbid psychological conditions as well as suicidal ideation and suicide (Danese et al., 2008; Gupta, 2013; Maia et al., 2007; Martin, Marchand, & Boyer, 2009; Sareen et al., 2007; Slavich & Irwin, 2014; Suls & Bunde, 2005). Understanding risk factors that may interact to increase an officers’ risk of developing PTSD or depression is an important step to not only prevent and treat these psychological conditions, but to also reduce or prevent concomitant negative psychological and biological consequences.

Nijenhuis and Van der Hart (2011) define dissociation in trauma as “a division of an individual’s personality, that is, of the dynamic, biopsychosocial system as a whole that determines his or her characteristic mental and behavioral actions.” PD is dissociation that occurs at the time of the trauma (Candel & Merckelbach, 2004). PD phenomenology is thought to occur when an individual’s ability to cope with a traumatic event is overwhelmed (Birmes et al., 2003; Blanchard et al., 1996; Bryant, 2005, 2007; Marmar et al., 1996; Marmar et al., 1999). It has been described as an alteration in time or place and individuals often report feelings of depersonalization, altered perceptions of pain, feeling disconnected, or tunnel vision. It is thought to protect individuals from overwhelming distress during trauma (Dalenberg & Carlson, 2012; Marmar, Weiss, & Metzler, 1997; Parlar, Frewen, Oremus, Lanius, & McKinnon, 2016) and is associated with increased hypothalamic–pituitary–adrenal axis reactivity as well as impaired performance on measures of executive functioning, memory, and verbal recollection (Parlar et al., 2016). Similar responses have been noted in individuals with PTSD and depression as well as individuals who have reported childhood trauma (Molina-Serrano, Linotte, Amat, Souery, & Barreto, 2008). It has been suggested that the presence of PD and concomitant neurological changes may increase an individual’s risk of PTSD or depression (Hodgson & Webster, 2011; Inslicht et al., 2010; Johnson et al., 2001; Marmar et al., 1996; Ozer, Best, Lipsey, & Weiss, 2003). However, these relationships are inconsistently shown, possibly due to risk factors that modify the relationship between PD, PTSD, and depression (Molina-Serrano et al., 2008). Prior trauma may be one of these risk factors. It is an excellent candidate, because it is independently associated with PD, PTSD, and depression (Breslau, Chilcoat, Kessler, & Davis, 1999; Breslau, Pe-terson, & Schultz, 2008; DiGangi et al., 2013; Komarovskaya et al., 2014; Ozer et al., 2003; Youngner et al., 2012).

Following a traumatic event, rates of PTSD and depression have been found to be higher in first responders who have reported prior trauma (Breslau et al., 1999; Breslau et al., 2008; Komarovskaya et al., 2014; Nolen-Hoeksema & Morrow, 1991; Ozer et al., 2003). Paramedics who reported a previous history of childhood abuse and neglect were more likely to report feelings of depression and acute stress after responding to a critical incident (Maunder, Halpern, Schwartz, & Gurevich, 2012). In 441 Mississippi officers and firefighters who worked during Hurricane Katrina, PD, PTSD, and depression were associated with early-life victimization (Komarovskaya et al., 2014). A direct relationship between family history of drug and alcohol abuse and anxiety/mood disorders was found with PD and an indirect relationship with PTSD (Inslicht et al., 2010). Among individuals with depression, dissociative symptoms occurred significantly more often in individuals who reported prior trauma than those who didn’t (Molina-Serrano et al., 2008). Although these results indicate an interrelationship between prior trauma, PD, PTSD, and depression, to the best of our knowledge, none of these studies evaluated whether prior trauma modified the relationship between PD and symptoms of PTSD, or PD and symptoms of depression in police officers. This is an important step toward increasing our understanding of the etiology of PTSD and depression, to increase our ability to identify officers at greatest risk, and to improve our ability to treat and prevent PTSD and depression in this population.

In the present study we examined whether PD is associated with symptoms of depression and PTSD, and if this association was modified by prior trauma in police officers. Our hypothesis was that symptoms of PTSD and depression would be higher in officers who reported prior trauma relative to those who did not.

Materials and Method

Participants and Procedure

The Buffalo Cardio-Metabolic Occupational Police Stress (BCOPS) study was a cross-sectional study conducted between 2004 and 2009. This study was designed to investigate the association between police stressors and physiological and psychological health consequences. All 710 Buffalo, New York active-duty police officers were asked to participate. No specific inclusion criteria were used other than the participant had to be a sworn police officer and sign an informed consent. Female officers who were pregnant at the time of the examination were excluded (n = 2), because a state of pregnancy changes all of the normal physiological measures. The State University of New York at Buffalo served as the data-collection site. Details of the study design are described elsewhere (Violanti et al., 2006). Briefly, officers completed self- and interviewer-administered questionnaires to provide information on demographic characteristics, lifestyle behaviors, psychological measures, and medical history. The PDE and Brief Trauma Questionnaires (PDEQ, BTQ; Marmar et al., 1997; Derogatis & Melisaratos, 1983, respectively) were not introduced into the study until 6 months after the study was initiated. Therefore, of the 464 officers who completed this study, 136 officers were missing PD, PTSD, or prior trauma data and were excluded from the analyses. With the exception of age, the 136 missing officers did not differ significantly from the officers who were included in the study on any of the study variables. The mean age of the study population was 41.6 years old (SD = 8.9) compared with 43.4 years (SD = 7.4; p = .03) in the missing officers. The State University of New York at Buffalo and the United States Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health Human Subjects Review Board approved the study.

Measures

Assessment of PTSD symptoms

PTSD symptoms were measured using the Posttraumatic Stress Disorder Checklist–Civilian version (PCL-C; Weathers, Litz, Herman, Huska, & Keane, 1993). The PCL-C consists of 17 questions that evaluate the presence of PTSD symptoms over the last month on a 5-point scale ranging from 1 (not at all) to 5 (extremely). The symptoms are based on the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM–IV) symptom categories of re-experiencing, avoidance, and hyperarousal (American Psychiatric Association, 1994). An overall symptom-severity score is calculated by summing the scores for each question (range = 17–85); higher scores indicate more symptoms of PTSD. In this study, the mean PTSD symptom scores were 26.4 (SD = 8.0) for female officers and 26.0 (SD = 9.2) for male officers, with a Cronbach’s α of 0.89.

Assessment of symptoms of depression

Depressive symptoms were measured using the Center for Epidemiological Studies–Depression scale (CES-D; Radloff, 1977). The CES-D is a short scale used to measure the symptoms of depression in the general population. It consists of 20 items rated on a 4-point scale according to how often the symptom occurred in the past 7 days: 0 (rarely or none of the time, less than 1 day), 1 (some or little of the time, 1–2 days), 2 (occasionally or a moderate amount of the time, 3–4 days), and 3 (most of the time, 5–7 days). Scores for the CES-D range from 0 to 60, with higher scores indicating more symptoms of depression. An overall depressive symptom score is calculated by summing the scores for each question. In this study, the mean CES-D symptom scores were 7.75 (SD = 6.4) for female officers and 7.40 (SD = 6.6) for male officers, with a Cronbach’s of α 0.89.

Assessment of Peritraumatic Dissociation Experience

The PDEQ (Marmar et al., 1997) consists of 10 questions designed to measure state dissociation. It assess an individual’s experiences and reactions, such as depersonalization, out-of-body experiences, altered perceptions of pain, or feeling disconnected during and immediately following their most recent traumatic event or critical incident (Marmar et al., 1997). On a 5-point scale ranging from 1 (not at all true) to 5 (extremely true) officers were asked to respond to statements such as “I had moments of losing track of what was going on,” “I ’blanked out’ or ’spaced out’ or in some way felt that I was not part of what was going on,” or “I felt confused; that is, there were moments when I had difficulty making sense of what was happening” (Marmar et al., 1997). An overall PDEQ score is calculated by summing the scores, with higher scores indicating more symptoms. In this study, the mean PDEQ scores were 15.0 (SD = 6.0) for female officers and 13.7 (SD = 5.0) for male officers, with a Cronbach’s α of 0.89.

Assessment of prior trauma

A modified version of the BTQ was used for this study (Derogatis & Melisaratos, 1983). This assessment was used because it includes an explicit assessment of PTSD Criterion Al, it has been shown to be related to higher dissociation scores, and because it is brief. The BTQ assesses 10 different traumatic events such as combat, serious car accident, natural or technological disaster, life-threatening illness, physical assault, unwanted sexual contact, and being seriously injured. For this study, the BTQ was modified in two ways; the first was that the introduction was changed from “The following questions ask about events that may be extraordinarily stressful or disturbing for almost everyone” to “Prior to coming into police work, have you had experiences in your life which you would consider traumatic?” Second, the question asking “Has a close family member or friend died violently for example, in a serious car crash, mugging, or attack?” was omitted and an open-response item included, which allowed the officers to describe any other traumatic event not otherwise listed. For all other questions, the officers were asked to respond either yes or no. If the officers responded yes to any of the questions, or listed an event in the open-response question, they were counted as having had a trauma prior to police work; otherwise they were counted as not having a trauma prior to police work. In this study, the mean number of prior traumas reported by female officers was 0.95 (SD = 1.4) and 1.2 (SD = 1.5) for male officers. The Cronbach’s α was 0.89.

Assessment of Covariates

Basic demographic characteristics, lifestyle behaviors, and medical history were collected through self- and interviewer-administered questionnaires and physical examination. Marital status originally consisted of six categories that were ultimately combined into three groups (single, divorced, and married). Educational status was elected from eight choices that ranged from “less than 12 years of school” to “graduate degree.” To permit adequate numbers in each category, these eight choices were collapsed into only two levels, ≤12 years/GED and ≥12 years/GED. Although ethnicity could be selected from six different categories (e.g., no, not Spanish/Hispanic/Latino/Latina; yes, other Spanish/Hispanic/Latino/Latina) and race from 15 different categories (e.g., Caucasian, Black or African American, American Indian, or Alaskan Native, Asian Indian, Chinese, Samoan), all the officers selected either Caucasian, African American, or Hispanic. Due to small numbers, and to protect participant confidentiality, the Caucasian and Hispanic groups were combined. Officer rank included police officer, sergeant/lieutenant, captain/detective, and other, but was collapsed into two categories: police officer and other due to small numbers. Previous military history was collected as either yes or no. Smoking status was collected as former, current, or never.

Statistical Analysis

Descriptive statistics were used to characterize the study population. Regression models were used to assess if PD was associated with either symptoms of PTSD or symptoms of depression. An interaction test was used to assess Effect Modification × Prior Trauma in the associations between PD and PTSD and PD and depression. Stratification by prior trauma was used to present the results.

Confounders were identified based on the literature, or because they were associated with both the dependent and independent variables. Race, sex, number of alcoholic drinks per week, and smoking were identified as potential confounders and all models were adjusted for these confounders.

Results

The mean age of the police officers is 41.6 (SD = 8.9) and the average years served on the force is 14.4 (SD = 8.4) years. Seventy-six percent of the population is male. Approximately 72% of officers were of the rank “police officer” (see Table 1). Eighty percent of the population was Caucasian/Hispanic and 20% African American. Most of the officers obtained at least a high school education (89.7%); most of them did not have military experience (72.4%). On average, they drank five (SD = 8.2) alcoholic beverages per week (see Table 1).

Table 1.

Associations of Selected Characteristics of the Study Population With Gender

Characteristics All
(n = 328)
M ± SD 		Female
(n = 79)
M ± SD 		Male
(n = 249)
M ± SD
Age 41.6 (8.9)   40.8 (6.8)   41.9 (9.5)  
Years of service 14.4 (8.4)   12.3 (6.5)   15.1 (8.8)  
Drinks per week 5.02 (8.2)   3.84 (6.4)   5.40 (8.7)  
Sleep quality 6.57 (3.3)   6.96 (3.6)   6.44 (3.2)  
PCL-C 26.1 (8.9)   26.4 (8.0)   26.0 (9.2)  
CES-D 7.49 (6.5)   7.75 (6.4)   7.40 (6.6)  
Prior trauma 1.15 (1.5)   .95 (1.4)   1.21 (1.5)  
PD 14.0 (5.3)   15.0 (6.0)   13.7 (5.0)  
N (%)     N (%)     N (%)    
Race/ethnicity
 Caucasian/Hispanic 251 (79.7) 59 (75.6) 192 (81.0)
 African American 64 (20.3) 19 (24.4) 45 (19.0)
Education
 ≤12 years/GED 33 (10.3) 4 (5.1)   29 (12.0)
 ≥12 years/GED 286 (89.7) 74 (94.9) 212 (88.0)
Marital Status
 Single 37 (11.6) 16 (20.5) 21 (8.7)  
 Married 231 (72.4) 45 (57.7) 186 (77.2)
 Divorced 51 (16.0) 17 (21.8) 34 (14.1)
Military experience
 No 231 (72.4) 67 (85.9) 164 (68.1)
 Yes 88 (27.6) 11 (14.1) 77 (31.9)
Rank
 Police officer 231 (72.4) 65 (83.3) 166 (68.9)
 Other* 88 (27.6) 13 (16.7) 75 (31.1)
Smoking status
 Current 58 (18.2) 23 (30.2) 35 (14.5)
 Former 76 (23.9) 22 (29.0) 54 (22.3)
 Never 184 (57.9) 31 (40.8) 153 (63.2)
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Note. PCL-C = Posttraumatic Stress Disorder Checklist–Civilian; CES-D = Center for Epidemiological Studies–Depression scale; PD = peritraumatic dissociation.

*

Other includes sergeant, lieutenant, captain, detective, and other.

After adjusting for covariates, PD was positively associated with symptoms of PTSD (β = 0.65, p < .001) and depression (β = 0.27, p < .001); as PD increased, so too did symptoms of PTSD and depression (see Table 2). Stratification of the models evaluating the association between PD, symptoms of PTSD, and depression by the presence or absence of trauma prior to police work indicated that prior trauma did not moderate the effect of PD on symptoms of PTSD, but did moderate the effect of PD on symptoms of depression (see Table 3). PD scores were positively associated with symptoms of PTSD in officers with (β = 0.75, p < .001) and without trauma prior to police work (β = 0.61, p < .001), which indicated that the association between PD and PTSD is not dependent on trauma prior to police work. In contrast to PTSD, PD scores were only significantly associated with symptoms of depression in officers with trauma prior to police work (β = 0.47, p < .001), but not in individuals without trauma prior to police work (β = 0.13, p = .17; see Figure 1). This indicates that trauma prior to police work does have a moderating effect on the association between PD and symptoms of depression. These results are further supported by the interaction results, which indicate that the effect of PD on symptoms of PTSD did not differ by the presence or absence of trauma prior to police work (p = .185), while the effect of PD on symptoms of depression did differ by the presence or absence of trauma prior to police work (p < .001).

Table 2.

Association Between Peritraumatic Dissociation With Posttraumatic Stress Disorder Symptoms and Symptoms of Depression

Peritraumatic Dissociation
Condition Model 1 β
(p value)		 Model 2 β
(p value)		 Model 3 β
(p value)
PTSD .69 (<.001) .72 (<.001) .65 (<.001)
Depression .31 (<.001) .31 (<.001) .27 (<.001)
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Note. Model 1: unadjusted; Model 2: adjusted for race; Model 3: adjusted for race, sex, number of drinks per week, and smoking status.

Table 3.

Association Between Peritraumatic Dissociation With Posttraumatic Stress Disorder Symptoms and Symptoms of Depression Stratified by Prior Trauma

Peritraumatic Dissociation
Prior Trauma Model 1 β
(p value)		 Model 2 β
(p value)		 Model 3 β
(p value)
NO
 PTSD .66 (<.001) .62 (<001) .61 (<.001)
 Depression .17 (<.041) .15 (<.083) .13 (<.165)
YES
 PTSD .68 (<.001) .84 (<.001) .75 (<.001)
 Depression .43 (<.001) .51 (<.001) .47 (<.001)
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Note. Model 1: unadjusted; Model 2: adjusted for race; Model 3: adjusted for race, sex, number of drinks per week, and smoking status.

Interaction p values adjusted for race, sex, number of drinks per week, and smoking status: Prior Trauma × PTSD (p = .185); Prior Trauma × Depression (p < .001).

Figure 1.

Figure 1

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Effects of peritraumatic dissociation and prior trauma on symptoms of depression. An interaction test was used to assess how prior trauma might have modified the association between peritraumatic dissociation and symptoms of depression. Here, the regression coefficients are plotted showing that peritraumatic dissociation scores were significantly associated with symptoms of depression in officers with trauma prior to police work (β = 0.47, p < .001), but not in officers without trauma prior to police work (β = 0.13, p = 0.16; interaction p = .001). These results indicate that the association between peritraumatic dissociation and symptoms of depression is dependent on prior trauma. See the online article for the color version of this figure.

Discussion

We evaluated whether PD was associated with PTSD and depression and if this relationship was modified by trauma that took place prior to police work. First, we found that as PD increased, so too did both symptoms of depression and PTSD. Second, we found that trauma prior to police work moderated the effect of PD on symptoms of depression, but not PTSD.

Our findings are similar to previous studies that have reported associations between PD and PTSD and PD and depression (Hodgson & Webster, 2011; Inslicht et al., 2010; Johnson et al., 2001; Marmar et al., 1996; Ozer et al., 2003; Weiss, Marmar, Metzler, & Ronfeldt, 1995). Marmar et al. (1996, 1999) reported that PD was significantly associated with PTSD after controlling for factors such as level of exposure, distress, locus of control, and social support. Similarly, Johnson, Pike, and Chard, (2001) found a relationship between PD and both PTSD and depression.

Unlike our study, previous research has principally focused on evaluating the association between prior trauma and PTSD mediated by PD or trait dissociation (Inslicht et al., 2010; McCaslin et al., 2006). Using path analysis, Inslicht et al. (2010) found neither direct nor indirect effects when they evaluated if PD mediated the relationship between prior civilian trauma and PTSD in police recruits. In contrast, McCaslin et al. (2006) found that both trait dissociation and PD were important mediators between prior trauma and PTSD. When the relationship between PD, trait dissociation, and PTSD were evaluated, PD did not fully mediate the relationship between trait dissociation and PTSD, indicating that trait dissociation may be as important as PD in the relationship between prior trauma and PTSD (McCaslin et al., 2006). Future studies could evaluate this question.

Dissociative symptoms have been found to occur in individuals with depression, particularly among individuals with a history of trauma (Molina-Serrano et al., 2008). These symptoms may be associated with neurocognitive dysfunction, particularly with memory and attention (Parlar et al., 2016). These researchers did not consider any association of PD and prior trauma with PTSD. Therefore, future longitudinal research is needed to clarify these relationships. Furthermore, because it is not standard to assess PD with depression, and because impaired neurological function may negatively impact treatment, assessing PD in officers who report depression may facilitate treatment (Parlar et al., 2016).

Strengths of this study include a high response rate, use of standardized protocol and measures, as well as investigation of a unique occupational cohort. However, several limitations should be kept in mind while interpreting the results of this study. Our study was cross-sectional, and as such, we cannot show any direction of causation. Information on PD, PTSD, and depression was obtained via self-report and was not clinically diagnosed, so lacked the clinical objectivity that might have helped participants more accurately assess and report their symptoms. Further, police officers may be reluctant to report symptoms of PTSD and depression; therefore the type and or severity of symptoms may be underreported (Gilmartin, 2002; Wester, Arndt, Sedivy, & Arndt, 2010). Another limitation is that some officers may have forgotten aspects of both the trauma event as well as the symptoms and severity of PD. This may have introduced recall bias into our results (Candel & Merckelbach, 2004). The results should not be generalized to all workers, but may be generalizable to other police departments of similar geographic location and size.

These results indicate that prior trauma modifies the association between PD and depression. Because PD is rarely assessed in individuals with depression and may impact treatment, these results could have implications for clinicians working with police officers who experience symptoms of depression, particularly in those who report prior trauma (Parlar et al., 2016).

Acknowledgments

The findings and conclusions in this report are those of the authors and do not necessarily represent the views of NIOSH. This work was supported by the United States Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health (NIOSH) Grant 200-2003-01580.

Contributor Information

Erin C. McCanlies, Health Effects Laboratory Division, Biostatistics and Epidemiology Branch, National Institute for Occupational Safety and Health, Morgantown, West Virginia

Khachatur Sarkisian, Health Effects Laboratory Division, Biostatistics and Epidemiology Branch, National Institute for Occupational Safety and Health, Morgantown, West Virginia.

Michael E. Andrew, Health Effects Laboratory Division, Biostatistics and Epidemiology Branch, National Institute for Occupational Safety and Health, Morgantown, West Virginia

Cecil M. Burchfiel, Health Effects Laboratory Division, Biostatistics and Epidemiology Branch, National Institute for Occupational Safety and Health, Morgantown, West Virginia

John M. Violanti, Department of Epidemiology and Environmental Health, University at Buffalo, State University of New York

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