Psychological Trauma: Theory, Research, Practice, and Policy 2015, Vol. 7, No. 5, 465– 472

© 2015 American Psychological Association 1942-9681/15/$12.00 http://dx.doi.org/10.1037/tra0000057

Investigating the Dissociative Subtype of Posttraumatic Stress Disorder in a Sample of Traumatized Detained Youth Diana C. Bennett, Crosby A. Modrowski, Patricia K. Kerig, and Shannon D. Chaplo

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University of Utah In this study, we tested the validity of a dissociative subtype in a sample of 225 detained adolescents (142 boys, 83 girls) likely meeting full or partial criteria for posttraumatic stress disorder (PTSD). Competing theories of dissociation pose controversy regarding dissociation as a taxon versus a continuum, and results of the current study contribute to this debate by providing evidence of distinct group differences between those high and low in dissociation. Mixture modeling revealed 2 groups of youth with differing levels of depersonalization/derealization dissociative symptoms. Differences between the 2 groups of youth were investigated regarding trauma exposure and several posttraumatic reactions: posttraumatic stress symptoms (PTSS), emotion dysregulation, and emotional numbing. Compared with youth classified in the low-dissociation group, youth who exhibited high levels of dissociation demonstrated higher levels of total PTSS, posttraumatic symptom clusters of emotional numbing, intrusion, and associated features, as well as reporting more difficulties with emotion dysregulation. To test theory regarding the factors that increase the likelihood of persistent dissociation, bootstrapped regression analyses were performed to examine the possibility of an indirect effect of peritraumatic dissociation. Results consistent with statistical mediation suggested that the presence of peritraumatic dissociation at the time of trauma may contribute to the continuation of dissociative symptoms as a more generalized pattern. The results of the current study have implications for clinical treatment with traumatized youth. Keywords: dissociation, PTSD, emotion dysregulation, peritraumatic dissociation

2009). Further, Carlson, Yates, and Sroufe (2009) argued that it may be particularly valuable to view dissociation as a continuum rather than a taxon in studies of youth, given that some levels of dissociative symptoms are nonpathological and may even be developmentally appropriate among young people, for example, daydreaming or having imaginary friends. Therefore, it is important to investigate whether the dissociative subtype described in the DSM-5 applies to youth as well as adults. One group of youth that has been the focus of the small body of extant research on child and adolescent dissociation is involved in the juvenile justice (JJ) system. Rates of trauma exposure and posttraumatic stress symptoms are generally high among JJinvolved youth (see Kerig & Becker, 2010, 2012 for reviews), as are symptoms of dissociation. For example, research has demonstrated that dissociative symptoms among JJ-involved youth are associated with higher levels of trauma exposure, particularly intrafamilial trauma (Plattner et al., 2003), and that dissociation is linked to other forms of risky behavior, such as substance abuse (Carrion & Steiner, 2000), that may perpetuate involvement in the JJ system. However, none of this research has considered whether the youth sampled report clinically significant levels of PTSS or whether there is evidence in support of a dissociative subtype. Using a sample of detained youth affords the opportunity to investigate the possibility of a dissociative subtype in a sample of youth with high rates of trauma exposure, posttraumatic stress, and dissociative symptoms. In addition, many of these studies have included only boys, whereas some research suggests that girls might be especially vulnerable to developing symptoms of dissociation in the aftermath of trauma (Zona & Milan, 2011). Therefore, it is important for studies to include both girls and boys to

Recent revisions to the Diagnostic and Statistical Manual of Mental Disorders, 5th ed. (DSM-5; American Psychological Association, 2013) include a new dissociative subtype of PTSD. The rationale for this subtype was based on evidence gathered from studies of American (see Carlson, Dalenberg, & McCade-Montez, 2012 for a review) and international (e.g., Merckelbach, Horselenberg, & Schmidt, 2002; Nijenhuis, van Engen, Kusters, & van der Hart, 2001) populations suggesting an association between trauma, PTSD, and dissociation and converging evidence from epidemiological, neurobiological, psychometric, and treatment-outcome research demonstrating that a distinct subset of individuals with PTSD also exhibit dissociative symptoms (Lanius et al., 2014). However, the current literature supporting the existence of the dissociative subtype has a number of limitations. First, empirical support for the dissociative subtype has been drawn primarily from studies of adults and little examination of the validity of the subtype has been conducted in studies including young people. Clinically, dissociation may be less easily recognized in children than in adults, due to lack of consensus regarding which dissociative behaviors are considered pathological across development (Hornstein & Putnam, 1992; Putnam, 2000; Silberg & Dallam,

This article was published Online First May 25, 2015. Diana C. Bennett, Crosby A. Modrowski, Patricia K. Kerig, and Shannon D. Chaplo, Department of Psychology, University of Utah. Correspondence concerning this article should be addressed to Diana C. Bennett, Department of Psychology, 380 South 1530 East Room 502, University of Utah, Salt Lake City, UT 84112. E-mail: diana.bennett@ utah.edu 465

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investigate potential gender differences in the prevalence and correlates of a dissociative subtype. A second limitation of the empirical evidence to date in support of the dissociative subtype is that research has focused on samples characterized by the experience of single-incident stressors, which Terr (1991) termed “Type I” traumas. In contrast, both theorists (Ford, 2013; Herman, 1994; Schimmenti & Caretti, 2014) and researchers (Stein et al., 2013; Trickett et al., 2011) have suggested that experiencing cumulative trauma beyond a single, discrete event is differentially associated with dissociation. The experience of multiple traumas, termed polyvictimization (Finkelhor et al., 2011), is prevalent among samples at high risk for dissociation, such as traumatized youth in the juvenile justice system (Ford et al., 2013). However, researchers have not yet investigated the link between polyvictimization and dissociation in samples of adolescents. Therefore, further research is needed to determine whether the dissociative subtype is relevant to youth generally, as well as to youth with a cumulative trauma history, such as many involved in the juvenile justice system. In addition to the limitations of the empirical support for the dissociative subtype, another controversy that has arisen in the wake of the DSM-5 (APA, 2013) revisions concerns whether dissociation should be viewed as a distinct subtype or a dimensional construct. Although the DSM-5 identifies dissociation as a taxon, alternative theoretical models view dissociation as a variable representing a continuum of emotional modulation. In particular, Lanius and colleagues’ program of research (Lanius et al., 2010, Lanius, Brand, Vermetten, Frewen, & Spiegel, 2012) has supported the idea that dissociation represents a regulatory strategy and that those individuals high in dissociative features have a tendency toward overmodulation, whereas others, who evidence higher posttraumatic symptoms of re-experiencing and hyperarousal, fall on the side of undermodulation. In the present study, we compared youth high and low in dissociation on a number of relevant variables, and evidence of any distinct differences between youth high and low in dissociation contribute to the discussion of taxonomic versus continuous representations of dissociation. Validation of the dissociative subtype requires identifying significant differences between those youth classified as high in dissociation compared with those youth with clinically elevated PTSD symptoms who do not demonstrate significant dissociative symptoms. One theoretical model that offers a framework for identifying variables of interest relating to the dissociative subtype focuses on the role of emotion dysregulation in the posttraumatic stress response. For example, Horowitz (2011) proposed that PTSD comprises a disorder of dysregulated emotion, and the symptom clusters represent a feedback loop in which dysregulated emotions are modulated in an attempt to achieve equilibrium. The extreme poles of emotion dysregulation include underregulation, evidenced by difficulty controlling emotional impulses, and overregulation, evidenced by difficulty accessing emotional states (Cole, Michel, & Teti, 1994). Consistent with Horowitz’s (2011) model, underregulation may manifest in greater levels of reexperiencing and hyperarousal symptoms, whereas emotional overregulation may be evidenced by symptoms of posttraumatic emotional numbing, avoidance, and dissociation. This conceptualization of dissociation as a regulatory strategy has been widely discussed in the literature. For example, Waelde and colleagues

(2009) posited that dissociation might be most prevalent among those who are emotionally overwhelmed by recurrent thoughts or reminders of the trauma. Further, Lanius’s model of over- and undermodulation (Lanius et al., 2010) suggested that youth who have experienced chronic trauma may use dissociation as a regulatory strategy, and thus may report less emotional distress. However, empirical studies have yet to test these theoretical ideas, particularly among samples of youth. Following this theoretical framework, we investigated differences in youth high and low in dissociation across a variety of variables relating to trauma, PTSD symptoms, emotion dysregulation, and emotional numbing. Another limitation of the research to date on dissociation is a relative dearth of work dedicated to understanding the persistence of dissociative symptoms following trauma exposure. One likely precursor is peritraumatic dissociation. As posited by Lanius and colleagues (2010), peritraumatic dissociation may “compartmentalize” memories of the traumatic event and may thus lead to cognitive and emotional detachment from the experience. Generally, peritraumatic dissociation has been viewed as an influential factor in the development of later PTSS (e.g., Brewin et al., 2000; Ozer, Best, Lipsey, & Weiss, 2008), but little empirical evidence is available regarding whether peritraumatic dissociation is in fact related to more persistent dissociation. Although a handful of studies have examined the link between peritraumatic and later dissociation, these studies have typically only studied the acute persistence of dissociative symptoms for brief periods, such as several weeks after the trauma (e.g., Griffin et al., 1997; Murray et al., 2002). To date, no known studies have examined how peritraumatic dissociation is related to persistent dissociative tendencies among young people months to years after the trauma. To this end, this study examined peritraumatic dissociation as a potential mediator of the association between trauma exposure and persistent dissociation in a sample of traumatized adolescents. To summarize, the overarching goal of the current study was to validate the dissociative subtype of PTSD in a sample of traumatized adolescents drawn from a detained population. The first aim was to determine whether we could find evidence of distinct subtypes of youth high and low in dissociation using a mixturemodeling technique in structural equation modeling. The second aim was to test hypotheses regarding differences between these groups related to types of trauma exposure, PTSS, emotion dysregulation, and emotional numbing, providing information about whether there is evidence of a distinct dissociative subtype versus a continuum in this sample. Finally, our third aim was to examine peritraumatic dissociation as a mediator of the association between trauma exposure and persistent dissociative tendencies.

Method Participants Participants were drawn from a larger sample of 660 youth (484 boys, 176 girls) recruited from a juvenile detention center in the United States. The majority of youth (98.6%) were charged with two or more infractions ranging from status offenses to misdemeanors and felonies. For the current analyses, we included the 225 youth (142 boys, 83 girls) who likely met either full or partial Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM–IV–TR; APA, 2000) criteria for PTSD, given that

DISSOCIATION AMONG DETAINED YOUTH

nosis of PTSD (criteria A, B, C, and D) or a partial diagnosis (criterion A and two or more of B, C, or D). Following Steinberg et al. (2004), any items to which the youth answered a score of 2 or higher were considered clinically present. Of the 225 youth included in these analyses, 96 met (42.67%) full criteria for PTSD and the remaining 129 (57.33%) met criteria for partial PTSD based on the guidelines stated above. Although DSM criteria were used to determine inclusion in the current sample, descriptive statistics are displayed using the symptom clusters of the fivefactor dysphoric arousal model (Elhai et al., 2011), which has been demonstrated to better fit data across multiple samples, including youth in the JJ system (Bennett, Kerig, Chaplo, McGee, & Baucom, 2014). Peritraumatic dissociation. Peritraumatic dissociation was measured using an adapted version of the Peritraumatic Dissociative Experiences Questionnaire–Child version (PDEQ-C; Bui et al., 2011). The measure used in this study included eight items of the PDEQ-C, a self-report measure asking youth to rate their responses on a 5-point scale (␣ ⫽ .78), with higher scores indicating greater peritraumatic dissociation (e.g., “I felt like I was watching it happen to someone else”). Based on their answers on the PTSD-RI (Steinberg et al., 2004), youth were asked the eight PDEQ-C items in relation to their experiences during the trauma they selected (from the index) as the most upsetting. The PDEQ-C developers have reported adequate test–retest reliability as well as internal consistency. Dissociation. The Adolescent Dissociative Experiences Scale (A-DES; Armstrong, Putnam, Carlson, Libero, & Smith, 1997) is a 30-item self-report measure designed to assess dissociation in adolescents (ages 11–17) in four areas that are also averaged to form a total score: dissociative amnesia (␣ ⫽ .82), absorption and imaginative involvement (␣ ⫽ .76), depersonalization and dereal-

it is common for children and adolescents to meet only partial criteria while exhibiting symptoms significant enough to interfere with functioning (Cohen & Scheeringa, 2009). Youth ranged in age from 12 to 18 (M ⫽ 16.23, SD ⫽ 1.19); 57.8% identified as White/Caucasian, 3.6% Black/African American, 23.6% Hispanic/ Latino, 2.7% Native American/Alaskan Native, 4.0% Pacific Islander/Native Hawaiian, 6.7% multiracial, and 0.4% Asian American. Descriptive statistics are displayed in Table 1.

Measures

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PTSD status, PTSS, and trauma exposure. The University of California Los Angeles Posttraumatic Stress Disorder Reaction Index–Adolescent Version (PTSD-RI; Steinberg, Brymer, Decker, & Pynoos, 2004) is a widely used measure to screen for exposure to trauma and PTSS among youth. The first set of questions asked youth whether they had been exposed to each of 24 different types of traumatic events, summed to create a total trauma exposure score. Youth in the current sample reported experiencing an average of 9.74 (SD ⫽ 3.90) distinct traumatic events, and an average of 33 months had elapsed since the event rated to be most upsetting took place. The remaining questions asked youth to rate the extent to which they had experienced DSM–IV–TR (APA, 2000) criteria symptoms and associated features in the past month (e.g., “I have dreams about what happened or other bad dreams”), scored using a Likert-type scale ranging from 0 (none of the time) to 4 (most of the time). Seventeen items specifically measuring DSM–IV–TR criteria were summed to establish a PTSS total score (␣ ⫽ .75). An associated features scale was also created using eight items (␣ ⫽ .54) noted in the DSM–IV–TR to be associated with the experience of repeated trauma exposure. Youths’ scores on the PTSD-RI were used to determine whether they likely met full criteria for a DSM–IV–TR (APA, 2000) diag-

Table 1 Means and Standard Deviations for the High- and Low-Dissociative Clusters Low dissociation (n ⫽ 205)

High dissociation (n ⫽ 20)

Variable

Mean

SD

Mean

SD

t

p

Age Total types of trauma exposure Months since index trauma Total PTSS Associated features PTSS: Intrusion PTSS: Avoidance PTSS: Numbing PTSS: Dysphoric arousal PTSS: Anxious arousal A-Des: Total A-Des: Dissociative amnesia A-Des: Absorption/imaginative involvement A-Des: Passive influence A-Des: Depersonalization/derealization Emotion dysregulation Emotional numbing Peritraumatic dissociation

16.23 9.66 33.15 37.77 15.05 11.05 13.96 11.19 10.11 4.17 2.61 3.00 2.50 3.12 2.20 92.41 10.45 23.75

(1.19) (3.91) (37.10) (9.68) (5.15) (4.17) (6.37) (5.25) (3.12) (2.17) (1.45) (1.97) (1.75) (1.88) (1.40) (20.40) (5.86) (7.61)

16.19 10.85 41.95 46.00 19.69 14.30 13.35 15.15 11.25 4.80 6.55 6.27 6.11 6.87 6.84 104.10 13.10 29.15

(1.19) (3.66) (45.92) (9.90) (3.74) (4.57) (6.71) (5.78) (2.05) (2.61) (1.27) (2.22) (1.88) (1.30) (0.99) (16.40) (5.70) (6.15)

0.16 ⫺1.31 ⫺0.99 ⫺3.62 ⫺3.50 ⫺3.29 0.41 ⫺3.19 ⫺1.60 ⫺1.22 ⫺11.68 ⫺6.99 ⫺8.33 ⫺8.72 ⫺14.40 ⫺2.48 ⫺1.94 ⫺3.07

.87 .19 .33 ⬍.001 .001 .001 .68 .002 .11 .23 ⬍.001 ⬍.001 ⬍.001 ⬍.001 ⬍.001 .01 .05 .002

Note. PTSS ⫽ Posttraumatic stress symptoms as measured by the UCLA Posttraumatic Stress Disorder Reaction Index; A-DES ⫽ Adolescent Dissociative Experiences Scale. Subscales include dissociative amnesia, absorption and imaginative involvement, passive influence, and depersonalization and derealization.

BENNETT, MODROWSKI, KERIG, AND CHAPLO

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ization (␣ ⫽ .86), and passive influence (␣ ⫽ .72). Cronbach’s ␣ for the total scale in the present sample was .94. Youth rated each item on an 11-point scale ranging from 0 (never) to 10 (always, e.g., “I feel like I’m in a fog or spaced out and things around me seem unreal”). Test–retest reliability and internal consistency have been established for the global score and four subscales, as has concurrent validity with other measures of dissociation (Farrington, Waller, Smerden, & Faupel, 2001). Emotion dysregulation. The Difficulties in Emotion Regulation Scale (DERS; Gratz & Roemer, 2004) is a 36-item self-report questionnaire designed to assess facets of emotion dysregulation (e.g., “When I’m upset, my emotions feel overwhelming”). Each item was rated on a 5-point scale ranging from 1 (almost never) to 5 (almost always), with higher scores indicating greater dysregulation. The total score was used in the present analyses (␣ ⫽ .90). Emotional numbing. The Emotional Numbing and Reactivity Scale (Orsillo et al., 2007) is a self-report measure designed to assess emotional responses to experiences. Each item was rated on a 5-point scale ranging from 1 (not at all typical of me) to 5 (entirely typical of me, e.g., “I feel cut off from my emotions”). The current study assessed general numbing of emotions (eight items, ␣ ⫽ .71), rescored so that higher scores indicated reports of greater numbness.

Procedure

types by allowing factor means for depersonalization or derealization symptoms to vary across groups. Mixture modeling uses full-information maximum likelihood and expectation– maximization to handle missing data. Using the most likely class assignment for each individual based on posterior probabilities, independent-samples t tests and ␹2 analyses were used to assess group differences. To test hypotheses regarding whether the patterns in these cross-sectional data were consistent with statistical mediation, multiple regression analyses were performed using Hayes’ (2013) PROCESS SPSS macro, which allows for the testing of models with bootstrapped confidence intervals (CIs). In mediation models, Path A indicates the direct association between the independent variable and mediator, Path B indicates the direct association between the mediator and dependent variable, Path C represents the association between the independent and dependent variables without the inclusion of the mediator, and Path C’ represents the indirect effect of the independent on the dependent variable including the mediator. In bootstrapped models, a significant indirect effect, as evidenced by the exclusion of 0 from the 95% CI, is consistent with statistical mediation.

Results Aim 1: Mixture Modeling to Create Groups

All study procedures were approved by the institutional review boards of the University of Utah and the Utah Department of Human Services. During visiting hours to the detention center, legal guardians provided signed informed consent, after which youth were invited to provide signed assent. Youth interviews were conducted individually by a research assistant in a private room within the detention center. To eliminate any perceptions of coercion for participation, no incentives were offered.

Data Analysis Mplus Version 6.11 (Muthén & Muthén, Los Angeles, CA) was programmed to create two classes consistent with the DSM-5 (APA, 2013) model of dissociative versus nondissociative sub-

Using mixture modeling, two classes were identified based on mean depersonalization/derealization dissociative symptoms: 205 youth were placed in Class 1, labeled “low dissociation,” and the remaining 20 youth were classified in Class 2, or “high dissociation” (the Akaike information criterion; AIC ⫽ 911.73 and the Bayesian information criterion; BIC ⫽ 925.41). Descriptive statistics by class are presented in Table 1, and intercorrelations among variables are displayed in Table 2. The Vuong–Lo– Mendell–Rubin likelihood-ratio test suggested that a two-class model fit significantly better than a one-class model (H0 log likelihood ⫽ ⫺465.17, p ⬍ .001). Average latent-class probabilities for most likely latent-class membership were .97 and .87, respectively, with off-diagonal probabilities of .03 and .13 and

Table 2 Correlations Among Study Variables Symptom 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

TE PTSD INT PN AV DA AA PERI DIS ER NB

1 —

2 ⴱⴱ

.32 —

3 ⴱⴱ

.24 .76ⴱⴱ —

4 ⴱⴱ

.27 .65ⴱⴱ .21ⴱⴱ —

5

6 ⴱⴱ

.18 .64ⴱⴱ .50ⴱⴱ .26ⴱⴱ —

7 ⴱⴱ

.23 .58ⴱⴱ .31ⴱⴱ .35ⴱⴱ .21ⴱⴱ —

.03 .36ⴱⴱ .21ⴱⴱ ⫺.08 .18ⴱⴱ .20ⴱⴱ —

8

9 ⴱⴱ

.31 .34ⴱⴱ .29ⴱⴱ .30ⴱⴱ .19ⴱⴱ .24ⴱⴱ ⫺.02 —

ⴱⴱ

.18 .45ⴱⴱ .30ⴱⴱ .44ⴱⴱ .17ⴱⴱ .33ⴱⴱ .07 .30ⴱⴱ —

10

11

.07 .45ⴱⴱ .27ⴱⴱ .45ⴱⴱ .15ⴱ .37ⴱⴱ .02 .15ⴱ .35ⴱⴱ —

.14ⴱ .31ⴱⴱ .08 .43ⴱⴱ .12 .30ⴱⴱ .00 .08 .30ⴱⴱ .33ⴱⴱ —

Note. N ⫽ 225; TE ⫽ trauma exposure; PTSD ⫽ posttraumatic stress disorder; INT ⫽ intrusion; PN ⫽ posttraumatic numbing; AV ⫽ avoidance; DA ⫽ dysphoric arousal; AA ⫽ anxious arousal; PERI ⫽ peritraumatic dissociation; DIS ⫽ dissociation; ER ⫽ emotion regulation; NB ⫽ emotional numbing (from Emotional Numbing and Reactivity Scale). ⴱ p ⬍ .05. ⴱⴱ p ⬍ .01.

DISSOCIATION AMONG DETAINED YOUTH

entropy of .86 indicating the degree of misclassification. As specified, the high-dissociation group reported significantly higher levels of depersonalization and derealization symptoms than the low-dissociation group, M ⫽ 6.37, SE ⫽ 0.51 versus M ⫽ 2.22, SE ⫽ 2.13.

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Peritraumatic Dissociation

.59 (.13) CI = [.35, .85] Path a

.07 (.02) CI = [.03, .09] Path b

Path c

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Aim 2: Group Differences We also examined differences between the groups in regard to trauma exposure and PTSS. The high-dissociation group reported significantly higher levels of PTSS than the low-dissociation group, and similar patterns emerged for associated features of PTSS, posttraumatic symptom clusters of numbing and intrusion, as well as emotion dysregulation. Results of independent-samples t tests are displayed in Table 1. There was no significant difference between the two groups in the number of traumatic events they had experienced or in the amount of time since their most upsetting event. The two groups were also compared on the subscales of the A-DES (Armstrong et al., 1997) to determine whether specific subscale differences were contributing to the group differences. The high-dissociation group reported greater dissociative symptoms on all four subscales of the A-DES (dissociative amnesia, absorption and imaginative involvement, passive influence, and depersonalization/derealization) as well as the total score, as displayed in Table 1. Notably, the high-dissociation group also scored higher than the low-dissociation group on general emotional numbing, although this difference did not reach statistical significance (p ⫽ .054). The two groups did not differ on the variables of gender, age, or ethnicity.

Aim 3: Mediation Model Results from the mediation model, which included all 225 youth from the previous analyses, were consistent with statistical mediation of the association between trauma exposure and persistent dissociation by way of peritraumatic dissociation, as evidenced by the absence of 0 in the CI indirect bootstrapped effect, B ⫽ .04, SE ⫽ .01, 95% CI ⫽ [.02, .07]. The mediation model and associated statistics are displayed in Figure 1. Although there was no significant direct effect (Path c) between trauma exposure and persistent dissociation, we proceeded with tests for an indirect effect, given recent theory and methodological research recommending that such an association is not required for mediated effects to be present (Hayes, 2009; MacKinnon & Fairchild, 2009; MacKinnon, Krull, & Lockwood, 2000; MacKinnon, Lockwood, Hoffman, West, & Sheets, 2002; Shrout & Bolger, 2002). This model was also tested for moderation by gender on each of the paths. Results indicated no significant interactions with gender on any of the paths, although the indirect effect was significant only for boys, B ⫽ .04, SE ⫽ .02, 95% CI ⫽ [.01, .09] and not girls, B ⫽ .03, SE ⫽ .02, 95% CI ⫽ [–.01, .09].

Discussion The first aim of this study was to examine whether there was statistical evidence for a dissociative subtype of PTSD in a sample of traumatized detained youth with clinically elevated levels of PTSD. We identified a subgroup of youth high in dissociation using advanced statistical techniques. Our second aim was to

Trauma Exposure

.05 (.03)

CI = [-.02, .11]

Dissociation

Path c’ .04 (.01)

CI = [.02, .07]

Figure 1. Mediation of the association between trauma exposure and dissociation by way of peritraumatic dissociation. Unstandardized B coefficients are displayed with standard errors in parentheses, followed by 95% CI. Trauma exposure indicates total trauma exposure measured by the PTSD-RI, dissociation indicates total score from the A-DES, peritraumatic dissociation is measured by the PDEQ-C. Path c indicates the association between trauma exposure and dissociation without inclusion of a mediator. Path c’ indicates the indirect effect of trauma exposure on dissociation via peritraumatic dissociation as a mediator. Paths a, b, and c’ are significant as evidenced by the exclusion of 0 from the 95% CI.

determine whether differences between these two groups support a dissociative subtype versus a conceptualization of dissociation on a continuum. In this regard, a number of meaningful differences between youth high and low on depersonalization/derealization symptoms emerged, supporting the validity of a dissociative subtype, although notably, only five youth in the sample denied experience of any persistent dissociative symptoms. Comparisons between groups indicated that, compared with those low in dissociation, youth high in dissociation reported more symptoms of PTSS and associated features. Although the high-dissociation group did not report significantly more types of trauma exposure than the low-dissociation group, the measure did not assess repeated exposure or the number of incidents experienced. It is possible that rates of chronic or repeated trauma exposure may differ across groups, consistent with previous research (Stein et al., 2013; Trickett et al., 2011). Finally, we found evidence suggesting that peritraumatic dissociation may be an important mechanism through which a more persistent dissociative style may develop. Overall, the group differences we identified support the notion that, in this JJ-involved sample, the high-dissociative group appeared to be experiencing greater functional impairment than the low-dissociative group. The high-dissociation group endorsed higher levels of emotion dysregulation as well as posttraumatic numbing and intrusion, per the PTSS subscales. Although theorists have suggested that PTSS symptoms may operate phasically, representing the individual’s attempt to achieve emotional equilibrium (Horowitz, 2011), the present results suggest that at least among youth in this sample, those high in dissociation reported higher levels of dysregulation, including both overregulation and underregulation. Our findings are consistent with theories suggesting that trauma exposure results in attempts at self-regulation across a number of domains (Ford, 2013), and that dissociation may represent a form of extreme overregulation of affective arousal (Frewen & Lanius, 2006). Another goal of the study was to test the role of peritraumatic dissociation as a mediator of the relation between trauma exposure and persistent dissociation. Results indicated an indirect effect of

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trauma on dissociation via peritraumatic dissociation for boys, suggesting that youth who dissociate during a traumatic event may be more likely to exhibit dissociative symptoms in the aftermath of that event. These findings are consistent with prior research that has found associations between peritraumatic dissociation and persistent dissociation a few weeks after the trauma (e.g., Griffin, Resick, & Mechanic, 1997; Murray, Ehlers, & Mayou, 2002) as well as between both peritraumatic and persistent dissociation and PTSD severity (e.g., Briere, Scott, & Weathers, 2005; Sugar & Ford, 2012). Future research is necessary to better understand how peritraumatic dissociation influences the development of dissociative features following trauma, and prospective data will help account for the possibility that retrospective reports of peritraumatic reactions may be influenced by the passage of time (David et al., 2010). There were some gender differences in the findings that should be taken into account. First, although the pattern of associations was similar for boys and girls, peritraumatic dissociation acted as a mediator of the link between trauma exposure and persistent dissociation only for boys. The model was not moderated by gender on any specific paths, and thus it is possible that this gender difference is accounted for by the lower statistical power yielded by the smaller sample of girls than boys in the present analysis; therefore, this finding should be replicated in future research including larger samples. However, it is also possible that this finding is suggestive of meaningful gender differences in posttraumatic responding which should be empirically tested in further research. For example, some studies have found higher rates of dissociation in girls than boys in samples exposed to community violence (Zona & Milan, 2011). Thus, it is possible that girls have a greater propensity toward dissociation, which occurs through a variety of mechanisms, whereas for boys, persistent dissociation emerges specifically as a function of peritraumatic dissociative symptoms such as depersonalization and derealization. However, it is notable that in the current study, we did not observe differences in the proportion of boys and girls in the high- and lowdissociative groups, just as prior evidence for gender differences in dissociation has been mixed, both in samples of youth (Chaplo, Kerig, Bennett, & Modrowski, 2015; Farrington et al., 2001) and adults (Simeon et al., 2003; Waller & Ross, 1997). Another question for further research, however, is whether gender differences in dissociation may depend on the type of trauma youth experience (Hetzel-Riggin & Roby, 2013). For example, girls are more likely than boys to experience traumatic events that are highly related to dissociation, such as sexual abuse (Bernier et al., 2013; Trickett et al., 2011). In the current study, we did not examine results by trauma type, and therefore, differences in rates of persistent dissociation may emerge in future research incorporating type of trauma into the models tested. The current study has a number of strengths, including the examination of a dissociative subtype in youth with clinically elevated PTSS using advanced statistical techniques. However, the present results also should be viewed in light of some limitations. First, results are derived from youth self-report and therefore, future researchers should employ multi-informant, multimethod techniques. Second, the cross-sectional nature of the data limits our ability to make causal and temporal statements about the relations among trauma exposure, peritraumatic dissociation, and posttraumatic dissociation. This is especially important in light of

our mediational findings with peritraumatic dissociation, given that it is possible that peritraumatic and persistent dissociation may operate in a cyclical fashion, with the experience of peritraumatic dissociation strengthening likelihood of later dissociation, and those patterns increasing the likelihood for youth to use dissociation as a coping method during later trauma exposure. Future researchers should examine these associations using prospective, longitudinal data. Additionally, researchers have suggested that youth in chronically high-stress environments, especially those persisting across developmental periods and considered to be inescapable or uncontrollable, are most likely to display physiological hyporeactivity and engage in coping strategies of emotional detachment (Badanes, Watamura, & Hankin, 2011; see Morris & Rao, 2013, for a review). Therefore, a more comprehensive trauma measure that assesses the chronicity and frequency of each type of trauma an individual endorses is necessary for future studies to further clarify the results found here regarding whether chronic exposure and early-onset trauma, in addition to polyvictimization, are more likely to be associated with dissociation. Last, although JJ-involved youth constitute a sample in which trauma exposure and PTSD are highly prevalent, our results may not generalize to the larger population of adolescents. Results of the current study have a number of clinical implications for professionals working with traumatized youth. Given that peritraumatic dissociation plays a role in the association between trauma exposure and persistent dissociative symptoms, assessment of peritraumatic dissociation in the immediate aftermath of a traumatic experience might help clinicians to determine the likelihood that youth will develop later dissociative symptoms and more severe forms of PTSS. This would be especially pertinent for preventive interventions that are designed to be implemented soon after the traumatic event, such as the Child and Family Traumatic Stress Intervention (Berkowitz et al., 2011). Furthermore, given that youth high in persistent dissociation reported greater functional impairment across a number of posttraumatic symptoms, these youth may benefit from interventions that target dissociative symptoms and prioritize the promotion of emotion-regulation skills (Cloitre et al., 2002; Ford et al., 2012; Gudiño et al., 2014). In summary, this is one of the first studies to examine the utility of the dissociative subtype in a sample of youth. Results indicate that the dissociative subtype might have clinical utility for youth, and that youth high in dissociation report greater dysfunction across a number of posttraumatic reactions. Further, our results are suggestive of the role that peritraumatic dissociation may play in the development of problematic and persistent dissociative symptoms following trauma exposure. Future research is needed to further investigate the possibility that dissociation serves as an affect modulation strategy in the aftermath of trauma.

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Received November 24, 2014 Revision received February 6, 2015 Accepted March 30, 2015 䡲