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Cumulative traumatization associated with pathological dissociation in acute psychiatric inpatients
Psychiatry Research 230 (2015) 406–412
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Cumulative traumatization associated with pathological dissociation in acute psychiatric inpatients Chui-De Chiu a,b,n, Mei-Chih Meg Tseng c,d, Yi-Ling Chien e, Shih-Cheng Liao e, Chih-Min Liu c,e, Yei-Yu Yeh b, Hai-Gwo Hwu b,c,e a
Department of Psychology, The Chinese University of Hong Kong, Hong Kong SAR, The People's Republic of China Department of Psychology, National Taiwan University, Taipei, Taiwan c Department of Psychiatry, National Taiwan University, Taipei, Taiwan d Department of Psychiatry, Far Eastern Memorial Hospital, New Taipei City, Taiwan e Department of Psychiatry, National Taiwan University Hospital, Taipei, Taiwan b
art ic l e i nf o
a b s t r a c t
Article history: Received 5 November 2014 Received in revised form 16 August 2015 Accepted 16 September 2015 Available online 9 October 2015
Clinical studies of patients with dissociative disorders and prospective studies of childhood trauma survivors show inconsistent findings regarding the relationship between childhood trauma and dissociation. This study aims to resolve this inconsistency by investigating how dissociation is related to parental dysfunctions, general psychopathology, childhood trauma, and adulthood trauma. Specifically, we focus on the role of cumulative traumatization in pathological and non-taxon dissociation. Eighty acute psychiatric inpatients were administrated standardized measures on dissociation, perceived parental dysfunctions, traumatizing events, and general psychopathology. Parental dysfunctions and trauma correlated with both types of dissociation and general psychopathology. When general psychopathology and parental dysfunctions were controlled, a unique link between trauma and dissociation remained significant. Moreover, the pattern of relationships differed for non-taxon and pathological dissociations. The effect of childhood but not adulthood trauma was significant on non-taxon dissociation. In contrast, an interactive model incorporating both childhood and adulthood trauma was the best model for explaining pathological dissociation. Childhood trauma is important for developing non-taxon dissociation, and adulthood trauma exacerbates its effects on the emergence of pathological dissociation. Cumulative traumatization from childhood to adulthood should be incorporated into the trauma hypothesis of pathological dissociation. & 2015 Elsevier Ireland Ltd. All rights reserved.
Keywords: Child abuse Dissociation Parenting dysfunction Trauma
1. Introduction Traumatizing events at early developmental stages including sexual and physical maltreatment prevail in patients with dissociative pathology. Dissociation refers to an experienced loss of information or loss of control over mental processes that under normal circumstance would be available to conscious awareness, self-attribution, or control (Cardeña and Carlson, 2011). Approximately 91% of the patients with DSM-III multiple personality disorder endured either sexual or physical abuse during childhood (Coons et al., 1988; Ross et al., 1989, 1990b; Boon and Draijer, 1993). Approximately 62–74% of psychiatric patients who were diagnosed with a dissociative disorder from a structured n Corresponding author at: Department of Psychology, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong. Fax: þ852 2603 5019. E-mail address: [email protected] (C.-D. Chiu).
http://dx.doi.org/10.1016/j.psychres.2015.09.028 0165-1781/& 2015 Elsevier Ireland Ltd. All rights reserved.
diagnostic interview reported childhood sexual, physical, or emotional abuse (Saxe et al., 1993; Modestin et al., 1996; Tutkun et al., 1998; Şar et al., 2000; Foote et al., 2006). In contrast, the rates in patients without a dissociative disorder were between 11% and 26%. Childhood relational trauma inflicted by close others may provoke conflict between approaching and avoidance towards the attachment figure, leading to a maladaptive regulation strategy that detaches from a reminder of the trauma memory (Terr, 1991; Freyd, 1994). Childhood trauma may be an antecedent for dissociative pathology (Dalenberg et al., 2012). To clarify the role of childhood trauma in dissociative pathology, four prospective studies investigated the association between childhood trauma and dissociative experiences. Diverse samples including children from high-risk families (Ogawa et al., 1997), children from families referred to clinical home-visiting services (Dutra et al., 2009), survivors of childhood sexual abuse (Trickett et al., 2011), and those who had congenital anomalies and
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underwent traumatic medical procedures (Diseth, 2006) were followed from childhood or early adolescence to late adolescence or early adulthood. The results showed that dissociation correlated with traumatizing events, as measured at the same time period. Only one study documented that repeated traumatic medical procedures in early adolescence predicted dissociation in adulthood (Diseth, 2006), whereas the other three studies reported that traumatizing events in childhood did not predict dissociative experiences in adulthood (Ogawa et al., 1997; Dutra et al., 2009; Trickett et al., 2011). Instead, poor quality parenting behavior including the unavailability of psychological care and lack of affective involvement predicted the degree of dissociative experiences in early adulthood (Ogawa et al., 1997; Dutra et al., 2009). The conflicting findings regarding the relationship between childhood trauma and dissociation raise three issues. First, parental dysfunctions may fully account for the association between childhood trauma and dissociation observed in the clinical studies. In addition to the prospective studies, dissociative symptoms were associated with perceived maladaptive parenting styles including intrusive discipline and control and the absence of care in the nonclinical (Modestin et al., 2002) and clinical samples (Modestin et al., 1996). More importantly, one study of trauma survivors showed that the effect of sexual abuse on dissociative symptoms became non-significant when family pathology was controlled (Nash et al., 1993, but also see Draijer and Langeland, 1999, and Tyler et al., 2004). Because childhood trauma covaries with parental dysfunctions (Bousha and Twentyman, 1984), parental dysfunctions may account for the association between trauma and dissociation (Merckelbach and Muris, 2001; Lynn et al., 2014). This finding could refute the trauma hypothesis. Alternatively, there may exist a unique effect of trauma on dissociation in the clinical sample, as the strength of the association between trauma and dissociation was higher in the clinical than the non-clinical samples (Näring and Nijenhuis, 2005). Secondly, qualitatively different types of dissociation may exist and have differential relations with trauma (Putnam, 1995). Studies of dissociative experiences provided a clue to the distinction between non-taxon and taxon, or pathological, dissociation (Waller et al., 1996). Pathological dissociation, including depersonalization, severe gaps in awareness, and amnesia, appears to be malignant and severely interferes with occupational and social functions. Dissociative experiences indeed discriminate patients with a dissociative disorder from other clinical individuals without a dissociative disorder (Carlson et al., 1993). In contrast, non-taxon dissociation, such as absorption, imaginative involvement, and minor gaps in awareness, does not necessarily interfere with daily functions (Carlson, 1994). These types of dissociative experiences prevail in the non-clinical populations (Ross et al., 1990a). Nontaxon dissociative experiences may be a building block, but they are not sufficient for the development of pathological dissociation. Among the 28 items of the Dissociative Experiences Scale (DES), a widely used screening instrument (Bernstein and Putnam, 1986) and the scale used in the prospective studies (Ogawa et al., 1997; Dutra et al., 2009; Trickett et al., 2011), 20 items cannot effectively differentiate clinical patients with a dissociative disorder from non-clinical dissociative individuals (Waller et al., 1996). This instrument may assess non-taxon dissociation. The null relationship between childhood trauma and later dissociative experiences observed in the prospective studies may have arisen from using the DES in the studies. Thirdly, in addition to childhood trauma, adulthood trauma may contribute to dissociative pathology. Prior research focused primarily on the effect of childhood traumatization on dissociation. Yet, one clinical study has shown that the clinical patients who underwent potentially traumatizing events in both adulthood and childhood had a higher dissociation score than those enduring
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traumatizing events in either childhood or adulthood (Lipschitz et al., 1996). Childhood trauma may lead to vulnerability to later stressors such as adulthood trauma. Thus, cumulative traumatization may be critical for the emergence of dissociative pathology. The importance of cumulative traumatization has been overlooked both in clinical studies (Coons et al., 1988; Ross et al., 1989, 1990b; Boon and Draijer, 1993; Saxe et al., 1993; Modestin et al., 1996; Tutkun et al., 1998; Şar et al., 2000; Foote et al., 2006) and in prospective studies (Ogawa et al., 1997; Dutra et al., 2009; Trickett et al., 2011). Adulthood trauma may prevail in dissociative patients in clinical studies, and the null results relating childhood trauma to later dissociation in the prospective studies may have arisen from not assessing adulthood trauma. Childhood trauma may be important, but adulthood trauma may sustain or exacerbate its effect on subsequent psychopathology including dissociation. If this is the case, a model including an interaction effect for childhood and adulthood trauma may increase the amount of explained variance in dissociation beyond the additive model with two independent effects for childhood and adulthood trauma. The aim of the current study is to address the unresolved issues regarding the relationship between trauma and dissociation. A clinical sample of unspecified psychiatric inpatients was recruited because dissociation prevails in several psychiatric disorders, including psychotic disorders (Schäfer et al., 2006) and mood disorders (Oedegaard et al., 2008). We examined whether a unique link exists between trauma and dissociation that is independent from parental dysfunctions as well as from general psychopathology. Controlling for general psychopathology is necessary because clinical patients with dissociation were frequently polysymptomatic, with symptoms of anxiety–depression, paranoia– psychosis, and panic–phobia (Steinberg et al., 2005; Vogel et al., 2009). General psychopathology may be confounded with the link between trauma and dissociation, and trauma may not act as a specific factor in the genesis of dissociation (Lynn et al., 2014). The finding of a unique link beyond parental dysfunctions and general psychopathology would strongly support the important role of trauma in the development of dissociation. On the basis of our literature review, we hypothesize that cumulative traumatization may play a critical role in pathological dissociation but not in nontaxon dissociation. If that is the case, a model incorporating an interaction between childhood and adulthood trauma should better account for pathological dissociation than for non-taxon dissociation.
2. Methods 2.1. Participants This study was approved of by the Institution Review Board at the National Taiwan University Hospital. Participants were recruited from two acute wards. One ward is for deficient reality testing or violent behaviors, primarily psychotic disorders and bipolar affective disorder (Ward-P); the other is for mood disturbances, anxiety, somatic complaints, or eating problems (WardN). Patients were eligible for this study if they were admitted for an acute psychiatric dysfunction (regardless of the clinical diagnosis but excluding organic brain syndromes) and if they were clinically stable after intervention. All participants, with their agreement, were referred to the principal researcher by four medical teams. Written informed consent was obtained after the procedure was explained. Eighty-nine participants were approached: 54% were from Ward-P, and 46% were from Ward-N. Seventy-three percent were female. The average of age was 367 12 years old. The primary clinical diagnoses of these participants included psychotic
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disorders (47%), bipolar affective disorder (26%), major depressive disorder (11%), eating disorders (9%), anxiety disorders (1%), and others (6%). All of the primary clinical diagnoses of the participants were made according to the DSM-IV-TR before their admission, and none was diagnosed with a dissociative disorder. Nine participants did not complete the assessment because of their unstable mental status. Data from 80 participants were used in the analysis.
subscales including somatization, obsession–compulsion, interpersonal sensitivity, depression, anxiety, hostility, phobia–anxiety, paranoid ideation, and psychoticism. Each item is rated on a 5-point scale from 0 (not at all) to 4 (extremely). A factor analysis showed a three-factorial solution including anxiety–depression, paranoia–psychosis, and panic–phobia in psychiatric outpatients (Steinberg et al., 2005). Thus, three factorial scales were calculated.
2.2. Instruments Dissociation. Two instruments were used. The DES is designed to capture the unusual daily experiences of dissociative individuals, including disturbances in attention, perception, and memory (Bernstein and Putnam, 1986). The DES comprises 28 items, each measured on an 11-point scale from 0 (never) to 100 (always). Conventionally, the scores of the 28 items are averaged. To have a precise indicator of non-taxon dissociation, a new score (DES-20) was calculated by excluding the eight taxon items that showed a pattern of results different from the other 20 items. The Traumatic Dissociation Scale (TDS) measures pathological dissociation (Eve Carlson, Lynn Waelde, et al., unpublished data). This instrument includes assessment of a sense of experiential disconnectedness that may include perceptual distortions about the self or the environment (depersonalization and derealization), an inability to access information or to control mental functions or behaviors that are normally amenable to such access or control (gap in awareness and amnesia), and a loss of continuity in subjective experience with accompanying involuntary and unwanted intrusions into awareness and behavior (for gaps in awareness and re-experiencing; see Cardeña and Carlson, 2011). The TDS has 24 items, and each item is measured on a 5-point scale from 0 (not at all) to 4 (more than once a day within one week). The validity of the TDS has been established in clinical patients and trauma survivors (Eve Carlson, Lynn Waelde, et al., unpublished data).1 The eight taxon items of the DES were not used as a measure of pathological dissociation because the limited number of items may reduce reliability (Watson, 2003) and validity (Simeon et al., 2003). Trauma history: The Brief Betrayal Trauma Survey (BBTS) is a measure of trauma history (Goldberg and Freyd, 2006). Twelve items include potentially traumatizing events (e.g., sexual, physical, or emotional abuse) inflicted by close (high-betrayal trauma) and non-close (low-betrayal trauma) others before 18 years old (childhood trauma) or after (adulthood trauma). Each experience is rated on a 3-point scale (never, one to two times, and more than two times) and converted into a dichotomous variable with a value of 0 (no) and 1 (yes). Four subscale scores were obtained, including time period (childhood versus adulthood trauma) and inflicting persons (high-versus low-betrayal trauma). Parental dysfunctions: The Measure of Parenting Style (MOPS) is a measure of the perceived dysfunctional parenting style of the participants’ mother and father before he or she was 16 years old (Parker et al., 1997). The scale is comprised of 20 items addressing respectively parental indifference (12 items) and over-control (8 items). Each item is scored from 0 (not true at all) to 3 (extremely true). Two subscale scores for indifference and over-control were obtained. General psychopathology: The Symptom Check List-90-Revised (SCL-90-R) is a scale that measures general psychopathology (Derogatis, 1983). The SCL-90-R contains 90 items, with nine 1 For the psychometric properties of the Chinese TDS in non-clinical samples, the internal consistency indexed by Cronbach’s alpha is 0.91 (N ¼445), the criterion-related validity indexed by Pearson’s correlation coefficient with the DES is 0.60 (N ¼445), and a six-week test–retest reliability using Pearson’s correlation coefficient is 0.80 (N ¼ 77).
2.3. Statistical analysis Three sets of analysis were conducted. To verify that the constructs of non-taxon dissociation and pathological dissociation are separable, we conducted an exploratory factor analysis on the items of the DES and the TDS. The principal factor method (factor extraction), parallel analysis (the determination of factor number), and the promax method (rotation) were adopted as they entail no distributional assumptions and are adequate for analyzing data with a small sample size (Fabrigar et al., 1999). The second set consisted of correlation analyses among the measured constructs using Spearman's correlation coefficient. These correlation coefficients can be used to cross-validate the relations linking dissociation with general psychopathology, parental dysfunctions, and potentially traumatizing events. The critical analysis was a hierarchical regression analysis (Cohen and Cohen, 1983) that examined the unique relationship between trauma and dissociation after removing the effects of general psychopathology and parental dysfunctions. All the scores of the dependent and independent variables were standardized in the regression models. Predictors are placed into the model in a forward fashion in accordance with the to-be-examined hypothesis.
3. Results 3.1. Non-taxon dissociation and pathological dissociation We first determined whether separable latent factors underlie the DES and TDS items. The parallel analysis found no evidence contradicting our prior assumption. There were two latent factors with an inter-factor correlation at 0.58, suggesting that common and unique mechanisms underlie non-taxon dissociation and pathological dissociation. The TDS items were loaded mainly on the first factor and the DES items on the second.2 3.2. Dissociation and general psychopathology Table 1 presents the descriptive statistics including means, standard deviations, and ranges of all measures. Positive correlations were found between the two dissociation scores and the total score of the SCL-90-R (for the DES-20 and TDS, ρs¼0.54 and 0.60, dfs¼76, pso0.0001). Both dissociation measures were positively correlated with all three factorial scales of the SCL-90-R (for the DES-20 and TDS, ρDissociation&Anxiety-depressions¼ 0.47 and 0.54, ρDissociation&Paranoid-psychotics¼ 0.50 and 0.57, ρDissociation&Panic-phobias ¼0.46 and 0.62, dfs¼76, pso0.0001). Consistent with the results reported from patients with a dissociative disorder (Steinberg et al., 2005) or mixed psychiatric inpatients (Vogel et al., 2009), dissociation was comorbid with diverse psychiatric dysfunctions. 2 The pattern of results of the following correlation and regression analyses remains the same when items with cross loadings on both factors were removed in the analysis.
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Table 1 The descriptive statistics for the measures used in this study. Measures
M
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Table 3 The results of hierarchical regression analyses examining the effects of parental dysfunctions and traumatizing events on dissociation.
SD
Range DES-20
Dissociation DES TDS
23.37 39.31
General psychopathology SCL-90-R
19.41 15.69
108.80
78.60
Parental dysfunctions MOPS-indifference MOPS-over-control
6.86 8.40
8.00 4.94
0–36 0–24
Traumatizing events BBTS-childhood trauma BBTS-adulthood trauma
2.15 2.48
2.38 2.58
0–10 0–10
4–293
Note: For abbreviations, DES ¼Dissociative Experiences Scale, TDS ¼Traumatic Dissociation Scale, SCL-90-R ¼Symptom Checklist 90 Revised, MOPS ¼ Measure of Parenting Style, and BBTS ¼Brief Betrayal Trauma Survey
Table 2 Spearman’s correlation coefficients among the measures.
1. DES-20 2. TDQ 3. SCL-90-R 4. MOPS-indifference 5. MOPS-over-control 6. BBTS-CT 7. BBTS-AT
1
2
0.64*** 0.52*** 0.34** 0.24* 0.45*** 0.49***
0.60*** 0.32** 0.25* 0.39*** 0.43***
3
0.28 0.32** 0.45*** 0.42***
4
0.36** 0.38*** 0.43***
β
0–84 24–94
5
0.29* 0.19
6
0.61***
Notes: For p-values, for abbreviations, DES-20 ¼ the DES without the eight taxon items, TDS ¼Traumatic Dissociation Scale, SCL-90-R ¼Symptom Checklist 90 Revised, MOPS ¼ Measure of Parenting Style, BBTS¼ Brief Betrayal Trauma Survey, CT¼childhood trauma, and AT ¼ adulthood trauma *
Designated for p o 0.05, For po 0.01, *** For p o 0.001. **
3.3. Dissociation, parental dysfunctions, and traumatizing events Table 2 presents the results of the correlation analysis between dissociation and the environmental risk factors. Moderate correlations were found between both types of dissociation and perceived parental dysfunctions. The two types of dissociation correlated positively with childhood trauma as well as with adulthood trauma. Notably, traumatizing events and perceived parental dysfunctions also positively correlated with general psychopathology.
Step 1 MOPS-I MOPS-C
Step 2 BBTS-CT
Step 3 BBTS-AT
Step 4 CT*AT
TDS P
β
T
P
0.10 0.89 0.02 0.20 ΔR2 ¼ 0.01
0.37 0.84
0.09 0.04 ΔR2 ¼0.02
0.87 0.38
0.38 0.70
0.22 2.00 ΔR2 ¼ 0.03
0.05
0.25 ΔR2 ¼0.04
2.35
0.02
0.21 1.81 ΔR2 ¼ 0.03
0.07
0.24 ΔR2 ¼0.06
2.04
o 0.05
0.05 0.61 ΔR2 o 0.01
0.55
0.20 ΔR2 ¼0.05
2.53
0.01
T
Note: For abbreviations DES-20 ¼ the DES without the eight taxon items, TDS¼ the Traumatic Dissociation Scale, MOPS-I or -C ¼ the indifference or over-control subscales, respectively, of the Measure of Parenting Style, and BBTS-CT or -AT ¼ the childhood or adulthood trauma subscale, respectively, of the Brief Betrayal Trauma Survey
dependent variable (ps4 0.30). Parental dysfunctions, independent from general psychopathology, did not explain any variances of the two dissociation scores. The results at Step 2 showed that childhood trauma significantly increased the amount of explained variances [for TDS and DES, F(1, 70)s¼5.51 and 3.99, ps ¼0.02 and 0.05]. Adding adulthood trauma in Step 3 significantly increased the amount of explained variances in pathological rather than in non-taxon dissociation [F(1, 69)s ¼5.13 and 3.28, ps¼0.03 and 0.07]. The results in Step 4 showed that the interaction explained the variances of the TDS score but not the variances of the DES-20 score [F(1, 68)s¼ 6.15 and 0.36, ps¼0.02 and 0.55]. The results from the hierarchical regression analysis suggested that cumulative traumatization, independent from general psychopathology and parental dysfunctions, uniquely contributes to pathological dissociation. To delineate the interaction effect of childhood and adulthood trauma on pathological dissociation, we reconstructed a multiple regression model of the TDS score using childhood and adulthood trauma and their interaction as the three predictors. Fig. 1 illustrates the results [for childhood trauma, adulthood trauma, and their interaction: βs¼0.14, 0.36, and 0.21; Ts¼1.05, 2.94, and 2.41; ps¼0.30, 0.005, and 0.02]. A high score on both childhood and adulthood trauma was associated with the highest score for pathological dissociation.
3.4. Cumulative trauma and dissociation 3.5. Level of betrayal and dissociation Table 3 presents the results of the hierarchical regression analysis.3 Two baseline models were constructed, with the total score of the SCL-90-R as the independent variable and the DES-20 and TDS score respectively as the dependent variable in each model. Scores on the indifference and over-control subscales were added into the baseline models in Step 1, and the incremental coefficients of determination (ΔR2) were not significant for either 3 To ascertain the potential effect of multi-colinearity on estimation, another set of hierarchical regression models was constructed using the residual scores of each preceding model to examine the effect of adding a new variable. The results remained the same as those using standardized raw scores.
Finally, the effect of the relationship with an abuser (i.e., level of betrayal) on dissociative pathology was analyzed (Freyd, 1994). Two multiple regression models were constructed, with three predictors including (a) potentially traumatizing events inflicted by close others (high-betrayal trauma); (b) potentially traumatizing events inflicted by non-close others (low-betrayal trauma); and (c) their interaction. Significant effects of high-betrayal trauma were reported on the total DES-20 and TDS scores [for the TDS and DES-20, βs¼0.41 and 0.32, F(1, 73)s¼2.42 and 3.01, pso0.01]. The effects of low-betrayal trauma on pathological dissociation approached a trend, and the effects on non-taxon dissociation were
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Fig. 1. The interaction effect of childhood and adulthood trauma on the TDS total score. The endorsement of a high level on both childhood and adulthood trauma scores had the greatest effect on pathological dissociation.
not significant [for the TDS and DES-20, βs ¼0.26 and 0.18, F(1, 73) s¼ 1.96 and 1.39, ps¼0.06 and 0.17]. The interaction effects were non-significant in both regression models (ps4 0.15).
4. Discussion This study aims to resolve three issues regarding the relationship between trauma and dissociation that emerge from clinical (Saxe et al., 1993; Modestin et al., 1996; Tutkun et al., 1998; Şar et al., 2000; Foote et al., 2006) and prospective studies (Ogawa et al., 1997; Dutra et al., 2009; Trickett et al., 2011) and to verify a hypothesis that cumulative traumatization accounts for pathological dissociation. The results showed that dissociation significantly correlated with traumatizing events, parental dysfunctions, and general psychopathology. A poly-symptomatic feature characterizes pathological dissociation, although the interpretation of the relationship between general psychopathology and dissociation requires clarification by future studies (e.g., general psychopathology as a genetic or familial covariate of dissociation, an associated feature of dissociation, or a secondary reaction to dissociation, Dalenberg et al., 2012). Importantly the results indicate that a unique link exists between trauma and dissociation beyond the contribution of general psychopathology and parental dysfunctions. Moreover, different patterns emerged for non-taxon dissociation and pathological dissociation. Non-taxon dissociation correlated solely with childhood trauma when parental dysfunctions and general psychopathology were controlled. In contrast, the interaction between childhood and adulthood trauma plays a more important role than childhood trauma in explaining the variances of pathological dissociation. The first unresolved issue in the literature relates to the role of parental dysfunctions in dissociation. Using a dimensional approach to measure parental behaviors (Locke and Prinz, 2002), our results showed that both indifference and over-control are correlated with non-taxon and pathological dissociation. However, both aspects of parental dysfunctions were associated with general psychopathology as well, and the link between parental dysfunctions and dissociation became non-significant when general psychopathology was controlled. Parental dysfunctions may not be a specific determinant of dissociation, supporting the idea that parental dysfunctions may be non-specific risk factors for psychopathology (Gladstone and Parker, 2005).
It should be noted that parental dysfunctions and relational trauma may overlap (Bousha and Twentyman, 1984) in emotional abuse, as revealed by the mild and moderate correlations between the measures of the MOPS and the BBTS. It is important for future research to determine which component of childhood maltreatments not measured in parental dysfunctions leads to dissociation. As revealed by the significant effects of high-level betrayal on dissociation, conflicts in attachment may play a central role (Freyd, 1994). These findings are consistent with the view that dissociation may represent a drastically incoherent and incompatible representation of self that results from abusive relationships with significant others. Cumulative exposure to potentially traumatizing events may maintain a pathological organization of personality inscribed in early disorganized attachment (Liotti, 1999). It is for future investigation to clarify whether a unique relationship exists between dissociation and conflicts in attachment (Lyons-Ruth et al., 2006). The second and third unresolved issues in the literature regard the relationship between trauma at different time periods and two types of dissociation. The results showed that non-taxon dissociation was primarily a contribution of childhood trauma. In contrast, the effect of childhood trauma on pathological dissociation became non-significant when childhood trauma, adulthood trauma, and their interaction were entered into a multiple regression model. This finding supports the distinction between non-taxon dissociation and pathological dissociation (Waller et al., 1996; Nijenhuis and van der Hart, 2011). Non-taxon dissociation may reflect a dissociation tendency that is related to childhood trauma, and this dissociation tendency may be the base for the development of pathological dissociation under cumulative traumatization. The finding that the interactive model increased the amount of explained variance of pathological dissociation supports our hypothesis. Our result is inconsistent with the view that a unique link between trauma and pathological dissociation may not exist (Merckelbach and Muris, 2001; Lynn et al., 2014). The interaction suggests that adulthood trauma may reactivate the morbid effect of childhood trauma on the emergence of pathological dissociation. Alternatively, childhood trauma that occurs during stress-sensitive periods of development may lead to a psychophysiological vulnerability for later stressors and subsequent psychopathology (Heim et al., 2010; Heim and Binder, 2012). Childhood trauma can contribute synergically with adulthood trauma to fuel the development of pathological dissociation. The trauma hypothesis that focuses on repeated childhood trauma should incorporate the important role of cumulative traumatization in the emergence of pathological dissociation. Some weaknesses of the study should be noted. Firstly, the cross-sectional nature of this study restricts any attempt to identify the causal relationship between trauma and dissociation. It is possible that pathological dissociation is an antecedent rather than a consequence of successive exposures to potentially traumatizing events into adulthood. Dissociative individuals may not learn trauma-related cues from previously adverse experiences (EbnerPriemer et al., 2009) or may have reduced socio-cognitive capacity and be unable to interpret a social or affect-charged situation accurately (DePrince, 2005). As a result, they subsequently cannot detect potential risks or protect themselves from harm. Secondly, due to the retrospective nature of the self-report, the veracity of the reported parenting behavior and potentially traumatizing events may be questionable. Few studies examine this possibility, and it is a question for further investigation. Yet, acceptable reliability and validity were noted for the retrospective report of parental style and potential traumatizing events (Brewin et al., 1996; Wilhelm et al., 2005). Two clinical studies also demonstrated that the trauma memory reported by dissociative individuals can be corroborated to a certain degree (Chu et al., 1999; Coons, 1994).
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Thirdly, there remains a debate on the dimensions of pathological dissociation. While some researchers consider amnesia, reflecting a disturbance of deliberately recollecting autobiographical memory, to be the hallmark of pathological dissociation (Putnam, 1997), others claim that the fragmented subjective sense of self is also vital (Nijenhuis and Van der Hart, 2011). Amnesia, but not identity-related items, is included in the TDS. One should be cautious about generalizing our results to identity-related dissociation. Further research is required to uncover the complex relationship between parental dysfunctions, traumatizing experiences, and different types of dissociation.
5. Conclusion Supporting the trauma hypothesis of dissociation, an intertwined association between trauma and dissociation was found in a clinical sample of acute psychiatric inpatients. The association remained significant when the effects of perceived parental dysfunctions and general psychopathology were controlled, excluding the potential confounding effects from these two covariates. More importantly, the results showed that the interaction between childhood trauma and adulthood trauma contributed to pathological dissociation whereas non-taxon dissociation was primarily accounted for by childhood trauma. The results not only support the importance of distinguishing pathological dissociation from non-taxon dissociation but also the importance of cumulative traumatization in the emergence of pathological dissociation. The cumulative effect of traumatizing events from childhood to adulthood and the two types of dissociation should be considered (i.e., non-taxon and pathological) in future studies on the pathogenetic trajectory of dissociative pathology. 1. For the psychometric properties of the Chinese TDS in nonclinical samples, the internal consistency indexed by Cronbach's alpha is 0.91 (N ¼445), the criterion-related validity indexed by Pearson's correlation coefficient with the DES is 0.60 (N ¼445), and a six-week test–retest reliability using Pearson's correlation coefficient is 0.80 (N ¼77). 2. The pattern of results of the following correlation and regression analyses remains the same when items with cross loadings on both factors were removed in the analysis. 3. To ascertain the potential effect of multi-colinearity on estimation, another set of hierarchical regression models was constructed using the residual scores of each preceding model to examine the effect of adding a new variable. The results remained the same as those using standardized raw scores.
Disclosures and acknowledgments All of the authors report that they have no competing interests. The preparation of this manuscript was supported by a start-up grant from The Chinese University of Hong Kong to CDC and a grant from the National Science Council to YYY (NSC 102-2420-H002-009-MY2). Correspondence can be sent to CDC or YYY. CDC is now at The Chinese University of Hong Kong, [email protected]. edu.hk. YYY is at National Taiwan University, [email protected]. We thank Bernet Elzinga for her comments on an early version of this manuscript. We thank Chen-Chung Liu, Ming-Hsien Hsieh, Hsian-Yuan Lin, Chih-Lin Chiang, Shao-Chien Chen, Chi-Te Lee, Chun-Yuan Chen, Chan-Hen Tsai, Chia-Yin Kuo, Wei-Shih Liu, WeiChih Kao, En-Nie Du, and Chien-Heng Lin for their assistance in participant recruitment and case consultation. We also thank the patients for their participation in this study.
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Cumulative traumatization associated with pathological dissociation in acute psychiatric inpatients Chui-De Chiu a,b,n, Mei-Chih Meg Tseng c,d, Yi-Ling Chien e, Shih-Cheng Liao e, Chih-Min Liu c,e, Yei-Yu Yeh b, Hai-Gwo Hwu b,c,e a
Department of Psychology, The Chinese University of Hong Kong, Hong Kong SAR, The People's Republic of China Department of Psychology, National Taiwan University, Taipei, Taiwan c Department of Psychiatry, National Taiwan University, Taipei, Taiwan d Department of Psychiatry, Far Eastern Memorial Hospital, New Taipei City, Taiwan e Department of Psychiatry, National Taiwan University Hospital, Taipei, Taiwan b
art ic l e i nf o
a b s t r a c t
Article history: Received 5 November 2014 Received in revised form 16 August 2015 Accepted 16 September 2015 Available online 9 October 2015
Clinical studies of patients with dissociative disorders and prospective studies of childhood trauma survivors show inconsistent findings regarding the relationship between childhood trauma and dissociation. This study aims to resolve this inconsistency by investigating how dissociation is related to parental dysfunctions, general psychopathology, childhood trauma, and adulthood trauma. Specifically, we focus on the role of cumulative traumatization in pathological and non-taxon dissociation. Eighty acute psychiatric inpatients were administrated standardized measures on dissociation, perceived parental dysfunctions, traumatizing events, and general psychopathology. Parental dysfunctions and trauma correlated with both types of dissociation and general psychopathology. When general psychopathology and parental dysfunctions were controlled, a unique link between trauma and dissociation remained significant. Moreover, the pattern of relationships differed for non-taxon and pathological dissociations. The effect of childhood but not adulthood trauma was significant on non-taxon dissociation. In contrast, an interactive model incorporating both childhood and adulthood trauma was the best model for explaining pathological dissociation. Childhood trauma is important for developing non-taxon dissociation, and adulthood trauma exacerbates its effects on the emergence of pathological dissociation. Cumulative traumatization from childhood to adulthood should be incorporated into the trauma hypothesis of pathological dissociation. & 2015 Elsevier Ireland Ltd. All rights reserved.
Keywords: Child abuse Dissociation Parenting dysfunction Trauma
1. Introduction Traumatizing events at early developmental stages including sexual and physical maltreatment prevail in patients with dissociative pathology. Dissociation refers to an experienced loss of information or loss of control over mental processes that under normal circumstance would be available to conscious awareness, self-attribution, or control (Cardeña and Carlson, 2011). Approximately 91% of the patients with DSM-III multiple personality disorder endured either sexual or physical abuse during childhood (Coons et al., 1988; Ross et al., 1989, 1990b; Boon and Draijer, 1993). Approximately 62–74% of psychiatric patients who were diagnosed with a dissociative disorder from a structured n Corresponding author at: Department of Psychology, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong. Fax: þ852 2603 5019. E-mail address: [email protected] (C.-D. Chiu).
http://dx.doi.org/10.1016/j.psychres.2015.09.028 0165-1781/& 2015 Elsevier Ireland Ltd. All rights reserved.
diagnostic interview reported childhood sexual, physical, or emotional abuse (Saxe et al., 1993; Modestin et al., 1996; Tutkun et al., 1998; Şar et al., 2000; Foote et al., 2006). In contrast, the rates in patients without a dissociative disorder were between 11% and 26%. Childhood relational trauma inflicted by close others may provoke conflict between approaching and avoidance towards the attachment figure, leading to a maladaptive regulation strategy that detaches from a reminder of the trauma memory (Terr, 1991; Freyd, 1994). Childhood trauma may be an antecedent for dissociative pathology (Dalenberg et al., 2012). To clarify the role of childhood trauma in dissociative pathology, four prospective studies investigated the association between childhood trauma and dissociative experiences. Diverse samples including children from high-risk families (Ogawa et al., 1997), children from families referred to clinical home-visiting services (Dutra et al., 2009), survivors of childhood sexual abuse (Trickett et al., 2011), and those who had congenital anomalies and
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underwent traumatic medical procedures (Diseth, 2006) were followed from childhood or early adolescence to late adolescence or early adulthood. The results showed that dissociation correlated with traumatizing events, as measured at the same time period. Only one study documented that repeated traumatic medical procedures in early adolescence predicted dissociation in adulthood (Diseth, 2006), whereas the other three studies reported that traumatizing events in childhood did not predict dissociative experiences in adulthood (Ogawa et al., 1997; Dutra et al., 2009; Trickett et al., 2011). Instead, poor quality parenting behavior including the unavailability of psychological care and lack of affective involvement predicted the degree of dissociative experiences in early adulthood (Ogawa et al., 1997; Dutra et al., 2009). The conflicting findings regarding the relationship between childhood trauma and dissociation raise three issues. First, parental dysfunctions may fully account for the association between childhood trauma and dissociation observed in the clinical studies. In addition to the prospective studies, dissociative symptoms were associated with perceived maladaptive parenting styles including intrusive discipline and control and the absence of care in the nonclinical (Modestin et al., 2002) and clinical samples (Modestin et al., 1996). More importantly, one study of trauma survivors showed that the effect of sexual abuse on dissociative symptoms became non-significant when family pathology was controlled (Nash et al., 1993, but also see Draijer and Langeland, 1999, and Tyler et al., 2004). Because childhood trauma covaries with parental dysfunctions (Bousha and Twentyman, 1984), parental dysfunctions may account for the association between trauma and dissociation (Merckelbach and Muris, 2001; Lynn et al., 2014). This finding could refute the trauma hypothesis. Alternatively, there may exist a unique effect of trauma on dissociation in the clinical sample, as the strength of the association between trauma and dissociation was higher in the clinical than the non-clinical samples (Näring and Nijenhuis, 2005). Secondly, qualitatively different types of dissociation may exist and have differential relations with trauma (Putnam, 1995). Studies of dissociative experiences provided a clue to the distinction between non-taxon and taxon, or pathological, dissociation (Waller et al., 1996). Pathological dissociation, including depersonalization, severe gaps in awareness, and amnesia, appears to be malignant and severely interferes with occupational and social functions. Dissociative experiences indeed discriminate patients with a dissociative disorder from other clinical individuals without a dissociative disorder (Carlson et al., 1993). In contrast, non-taxon dissociation, such as absorption, imaginative involvement, and minor gaps in awareness, does not necessarily interfere with daily functions (Carlson, 1994). These types of dissociative experiences prevail in the non-clinical populations (Ross et al., 1990a). Nontaxon dissociative experiences may be a building block, but they are not sufficient for the development of pathological dissociation. Among the 28 items of the Dissociative Experiences Scale (DES), a widely used screening instrument (Bernstein and Putnam, 1986) and the scale used in the prospective studies (Ogawa et al., 1997; Dutra et al., 2009; Trickett et al., 2011), 20 items cannot effectively differentiate clinical patients with a dissociative disorder from non-clinical dissociative individuals (Waller et al., 1996). This instrument may assess non-taxon dissociation. The null relationship between childhood trauma and later dissociative experiences observed in the prospective studies may have arisen from using the DES in the studies. Thirdly, in addition to childhood trauma, adulthood trauma may contribute to dissociative pathology. Prior research focused primarily on the effect of childhood traumatization on dissociation. Yet, one clinical study has shown that the clinical patients who underwent potentially traumatizing events in both adulthood and childhood had a higher dissociation score than those enduring
407
traumatizing events in either childhood or adulthood (Lipschitz et al., 1996). Childhood trauma may lead to vulnerability to later stressors such as adulthood trauma. Thus, cumulative traumatization may be critical for the emergence of dissociative pathology. The importance of cumulative traumatization has been overlooked both in clinical studies (Coons et al., 1988; Ross et al., 1989, 1990b; Boon and Draijer, 1993; Saxe et al., 1993; Modestin et al., 1996; Tutkun et al., 1998; Şar et al., 2000; Foote et al., 2006) and in prospective studies (Ogawa et al., 1997; Dutra et al., 2009; Trickett et al., 2011). Adulthood trauma may prevail in dissociative patients in clinical studies, and the null results relating childhood trauma to later dissociation in the prospective studies may have arisen from not assessing adulthood trauma. Childhood trauma may be important, but adulthood trauma may sustain or exacerbate its effect on subsequent psychopathology including dissociation. If this is the case, a model including an interaction effect for childhood and adulthood trauma may increase the amount of explained variance in dissociation beyond the additive model with two independent effects for childhood and adulthood trauma. The aim of the current study is to address the unresolved issues regarding the relationship between trauma and dissociation. A clinical sample of unspecified psychiatric inpatients was recruited because dissociation prevails in several psychiatric disorders, including psychotic disorders (Schäfer et al., 2006) and mood disorders (Oedegaard et al., 2008). We examined whether a unique link exists between trauma and dissociation that is independent from parental dysfunctions as well as from general psychopathology. Controlling for general psychopathology is necessary because clinical patients with dissociation were frequently polysymptomatic, with symptoms of anxiety–depression, paranoia– psychosis, and panic–phobia (Steinberg et al., 2005; Vogel et al., 2009). General psychopathology may be confounded with the link between trauma and dissociation, and trauma may not act as a specific factor in the genesis of dissociation (Lynn et al., 2014). The finding of a unique link beyond parental dysfunctions and general psychopathology would strongly support the important role of trauma in the development of dissociation. On the basis of our literature review, we hypothesize that cumulative traumatization may play a critical role in pathological dissociation but not in nontaxon dissociation. If that is the case, a model incorporating an interaction between childhood and adulthood trauma should better account for pathological dissociation than for non-taxon dissociation.
2. Methods 2.1. Participants This study was approved of by the Institution Review Board at the National Taiwan University Hospital. Participants were recruited from two acute wards. One ward is for deficient reality testing or violent behaviors, primarily psychotic disorders and bipolar affective disorder (Ward-P); the other is for mood disturbances, anxiety, somatic complaints, or eating problems (WardN). Patients were eligible for this study if they were admitted for an acute psychiatric dysfunction (regardless of the clinical diagnosis but excluding organic brain syndromes) and if they were clinically stable after intervention. All participants, with their agreement, were referred to the principal researcher by four medical teams. Written informed consent was obtained after the procedure was explained. Eighty-nine participants were approached: 54% were from Ward-P, and 46% were from Ward-N. Seventy-three percent were female. The average of age was 367 12 years old. The primary clinical diagnoses of these participants included psychotic
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disorders (47%), bipolar affective disorder (26%), major depressive disorder (11%), eating disorders (9%), anxiety disorders (1%), and others (6%). All of the primary clinical diagnoses of the participants were made according to the DSM-IV-TR before their admission, and none was diagnosed with a dissociative disorder. Nine participants did not complete the assessment because of their unstable mental status. Data from 80 participants were used in the analysis.
subscales including somatization, obsession–compulsion, interpersonal sensitivity, depression, anxiety, hostility, phobia–anxiety, paranoid ideation, and psychoticism. Each item is rated on a 5-point scale from 0 (not at all) to 4 (extremely). A factor analysis showed a three-factorial solution including anxiety–depression, paranoia–psychosis, and panic–phobia in psychiatric outpatients (Steinberg et al., 2005). Thus, three factorial scales were calculated.
2.2. Instruments Dissociation. Two instruments were used. The DES is designed to capture the unusual daily experiences of dissociative individuals, including disturbances in attention, perception, and memory (Bernstein and Putnam, 1986). The DES comprises 28 items, each measured on an 11-point scale from 0 (never) to 100 (always). Conventionally, the scores of the 28 items are averaged. To have a precise indicator of non-taxon dissociation, a new score (DES-20) was calculated by excluding the eight taxon items that showed a pattern of results different from the other 20 items. The Traumatic Dissociation Scale (TDS) measures pathological dissociation (Eve Carlson, Lynn Waelde, et al., unpublished data). This instrument includes assessment of a sense of experiential disconnectedness that may include perceptual distortions about the self or the environment (depersonalization and derealization), an inability to access information or to control mental functions or behaviors that are normally amenable to such access or control (gap in awareness and amnesia), and a loss of continuity in subjective experience with accompanying involuntary and unwanted intrusions into awareness and behavior (for gaps in awareness and re-experiencing; see Cardeña and Carlson, 2011). The TDS has 24 items, and each item is measured on a 5-point scale from 0 (not at all) to 4 (more than once a day within one week). The validity of the TDS has been established in clinical patients and trauma survivors (Eve Carlson, Lynn Waelde, et al., unpublished data).1 The eight taxon items of the DES were not used as a measure of pathological dissociation because the limited number of items may reduce reliability (Watson, 2003) and validity (Simeon et al., 2003). Trauma history: The Brief Betrayal Trauma Survey (BBTS) is a measure of trauma history (Goldberg and Freyd, 2006). Twelve items include potentially traumatizing events (e.g., sexual, physical, or emotional abuse) inflicted by close (high-betrayal trauma) and non-close (low-betrayal trauma) others before 18 years old (childhood trauma) or after (adulthood trauma). Each experience is rated on a 3-point scale (never, one to two times, and more than two times) and converted into a dichotomous variable with a value of 0 (no) and 1 (yes). Four subscale scores were obtained, including time period (childhood versus adulthood trauma) and inflicting persons (high-versus low-betrayal trauma). Parental dysfunctions: The Measure of Parenting Style (MOPS) is a measure of the perceived dysfunctional parenting style of the participants’ mother and father before he or she was 16 years old (Parker et al., 1997). The scale is comprised of 20 items addressing respectively parental indifference (12 items) and over-control (8 items). Each item is scored from 0 (not true at all) to 3 (extremely true). Two subscale scores for indifference and over-control were obtained. General psychopathology: The Symptom Check List-90-Revised (SCL-90-R) is a scale that measures general psychopathology (Derogatis, 1983). The SCL-90-R contains 90 items, with nine 1 For the psychometric properties of the Chinese TDS in non-clinical samples, the internal consistency indexed by Cronbach’s alpha is 0.91 (N ¼445), the criterion-related validity indexed by Pearson’s correlation coefficient with the DES is 0.60 (N ¼445), and a six-week test–retest reliability using Pearson’s correlation coefficient is 0.80 (N ¼ 77).
2.3. Statistical analysis Three sets of analysis were conducted. To verify that the constructs of non-taxon dissociation and pathological dissociation are separable, we conducted an exploratory factor analysis on the items of the DES and the TDS. The principal factor method (factor extraction), parallel analysis (the determination of factor number), and the promax method (rotation) were adopted as they entail no distributional assumptions and are adequate for analyzing data with a small sample size (Fabrigar et al., 1999). The second set consisted of correlation analyses among the measured constructs using Spearman's correlation coefficient. These correlation coefficients can be used to cross-validate the relations linking dissociation with general psychopathology, parental dysfunctions, and potentially traumatizing events. The critical analysis was a hierarchical regression analysis (Cohen and Cohen, 1983) that examined the unique relationship between trauma and dissociation after removing the effects of general psychopathology and parental dysfunctions. All the scores of the dependent and independent variables were standardized in the regression models. Predictors are placed into the model in a forward fashion in accordance with the to-be-examined hypothesis.
3. Results 3.1. Non-taxon dissociation and pathological dissociation We first determined whether separable latent factors underlie the DES and TDS items. The parallel analysis found no evidence contradicting our prior assumption. There were two latent factors with an inter-factor correlation at 0.58, suggesting that common and unique mechanisms underlie non-taxon dissociation and pathological dissociation. The TDS items were loaded mainly on the first factor and the DES items on the second.2 3.2. Dissociation and general psychopathology Table 1 presents the descriptive statistics including means, standard deviations, and ranges of all measures. Positive correlations were found between the two dissociation scores and the total score of the SCL-90-R (for the DES-20 and TDS, ρs¼0.54 and 0.60, dfs¼76, pso0.0001). Both dissociation measures were positively correlated with all three factorial scales of the SCL-90-R (for the DES-20 and TDS, ρDissociation&Anxiety-depressions¼ 0.47 and 0.54, ρDissociation&Paranoid-psychotics¼ 0.50 and 0.57, ρDissociation&Panic-phobias ¼0.46 and 0.62, dfs¼76, pso0.0001). Consistent with the results reported from patients with a dissociative disorder (Steinberg et al., 2005) or mixed psychiatric inpatients (Vogel et al., 2009), dissociation was comorbid with diverse psychiatric dysfunctions. 2 The pattern of results of the following correlation and regression analyses remains the same when items with cross loadings on both factors were removed in the analysis.
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Table 1 The descriptive statistics for the measures used in this study. Measures
M
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Table 3 The results of hierarchical regression analyses examining the effects of parental dysfunctions and traumatizing events on dissociation.
SD
Range DES-20
Dissociation DES TDS
23.37 39.31
General psychopathology SCL-90-R
19.41 15.69
108.80
78.60
Parental dysfunctions MOPS-indifference MOPS-over-control
6.86 8.40
8.00 4.94
0–36 0–24
Traumatizing events BBTS-childhood trauma BBTS-adulthood trauma
2.15 2.48
2.38 2.58
0–10 0–10
4–293
Note: For abbreviations, DES ¼Dissociative Experiences Scale, TDS ¼Traumatic Dissociation Scale, SCL-90-R ¼Symptom Checklist 90 Revised, MOPS ¼ Measure of Parenting Style, and BBTS ¼Brief Betrayal Trauma Survey
Table 2 Spearman’s correlation coefficients among the measures.
1. DES-20 2. TDQ 3. SCL-90-R 4. MOPS-indifference 5. MOPS-over-control 6. BBTS-CT 7. BBTS-AT
1
2
0.64*** 0.52*** 0.34** 0.24* 0.45*** 0.49***
0.60*** 0.32** 0.25* 0.39*** 0.43***
3
0.28 0.32** 0.45*** 0.42***
4
0.36** 0.38*** 0.43***
β
0–84 24–94
5
0.29* 0.19
6
0.61***
Notes: For p-values, for abbreviations, DES-20 ¼ the DES without the eight taxon items, TDS ¼Traumatic Dissociation Scale, SCL-90-R ¼Symptom Checklist 90 Revised, MOPS ¼ Measure of Parenting Style, BBTS¼ Brief Betrayal Trauma Survey, CT¼childhood trauma, and AT ¼ adulthood trauma *
Designated for p o 0.05, For po 0.01, *** For p o 0.001. **
3.3. Dissociation, parental dysfunctions, and traumatizing events Table 2 presents the results of the correlation analysis between dissociation and the environmental risk factors. Moderate correlations were found between both types of dissociation and perceived parental dysfunctions. The two types of dissociation correlated positively with childhood trauma as well as with adulthood trauma. Notably, traumatizing events and perceived parental dysfunctions also positively correlated with general psychopathology.
Step 1 MOPS-I MOPS-C
Step 2 BBTS-CT
Step 3 BBTS-AT
Step 4 CT*AT
TDS P
β
T
P
0.10 0.89 0.02 0.20 ΔR2 ¼ 0.01
0.37 0.84
0.09 0.04 ΔR2 ¼0.02
0.87 0.38
0.38 0.70
0.22 2.00 ΔR2 ¼ 0.03
0.05
0.25 ΔR2 ¼0.04
2.35
0.02
0.21 1.81 ΔR2 ¼ 0.03
0.07
0.24 ΔR2 ¼0.06
2.04
o 0.05
0.05 0.61 ΔR2 o 0.01
0.55
0.20 ΔR2 ¼0.05
2.53
0.01
T
Note: For abbreviations DES-20 ¼ the DES without the eight taxon items, TDS¼ the Traumatic Dissociation Scale, MOPS-I or -C ¼ the indifference or over-control subscales, respectively, of the Measure of Parenting Style, and BBTS-CT or -AT ¼ the childhood or adulthood trauma subscale, respectively, of the Brief Betrayal Trauma Survey
dependent variable (ps4 0.30). Parental dysfunctions, independent from general psychopathology, did not explain any variances of the two dissociation scores. The results at Step 2 showed that childhood trauma significantly increased the amount of explained variances [for TDS and DES, F(1, 70)s¼5.51 and 3.99, ps ¼0.02 and 0.05]. Adding adulthood trauma in Step 3 significantly increased the amount of explained variances in pathological rather than in non-taxon dissociation [F(1, 69)s ¼5.13 and 3.28, ps¼0.03 and 0.07]. The results in Step 4 showed that the interaction explained the variances of the TDS score but not the variances of the DES-20 score [F(1, 68)s¼ 6.15 and 0.36, ps¼0.02 and 0.55]. The results from the hierarchical regression analysis suggested that cumulative traumatization, independent from general psychopathology and parental dysfunctions, uniquely contributes to pathological dissociation. To delineate the interaction effect of childhood and adulthood trauma on pathological dissociation, we reconstructed a multiple regression model of the TDS score using childhood and adulthood trauma and their interaction as the three predictors. Fig. 1 illustrates the results [for childhood trauma, adulthood trauma, and their interaction: βs¼0.14, 0.36, and 0.21; Ts¼1.05, 2.94, and 2.41; ps¼0.30, 0.005, and 0.02]. A high score on both childhood and adulthood trauma was associated with the highest score for pathological dissociation.
3.4. Cumulative trauma and dissociation 3.5. Level of betrayal and dissociation Table 3 presents the results of the hierarchical regression analysis.3 Two baseline models were constructed, with the total score of the SCL-90-R as the independent variable and the DES-20 and TDS score respectively as the dependent variable in each model. Scores on the indifference and over-control subscales were added into the baseline models in Step 1, and the incremental coefficients of determination (ΔR2) were not significant for either 3 To ascertain the potential effect of multi-colinearity on estimation, another set of hierarchical regression models was constructed using the residual scores of each preceding model to examine the effect of adding a new variable. The results remained the same as those using standardized raw scores.
Finally, the effect of the relationship with an abuser (i.e., level of betrayal) on dissociative pathology was analyzed (Freyd, 1994). Two multiple regression models were constructed, with three predictors including (a) potentially traumatizing events inflicted by close others (high-betrayal trauma); (b) potentially traumatizing events inflicted by non-close others (low-betrayal trauma); and (c) their interaction. Significant effects of high-betrayal trauma were reported on the total DES-20 and TDS scores [for the TDS and DES-20, βs¼0.41 and 0.32, F(1, 73)s¼2.42 and 3.01, pso0.01]. The effects of low-betrayal trauma on pathological dissociation approached a trend, and the effects on non-taxon dissociation were
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Fig. 1. The interaction effect of childhood and adulthood trauma on the TDS total score. The endorsement of a high level on both childhood and adulthood trauma scores had the greatest effect on pathological dissociation.
not significant [for the TDS and DES-20, βs ¼0.26 and 0.18, F(1, 73) s¼ 1.96 and 1.39, ps¼0.06 and 0.17]. The interaction effects were non-significant in both regression models (ps4 0.15).
4. Discussion This study aims to resolve three issues regarding the relationship between trauma and dissociation that emerge from clinical (Saxe et al., 1993; Modestin et al., 1996; Tutkun et al., 1998; Şar et al., 2000; Foote et al., 2006) and prospective studies (Ogawa et al., 1997; Dutra et al., 2009; Trickett et al., 2011) and to verify a hypothesis that cumulative traumatization accounts for pathological dissociation. The results showed that dissociation significantly correlated with traumatizing events, parental dysfunctions, and general psychopathology. A poly-symptomatic feature characterizes pathological dissociation, although the interpretation of the relationship between general psychopathology and dissociation requires clarification by future studies (e.g., general psychopathology as a genetic or familial covariate of dissociation, an associated feature of dissociation, or a secondary reaction to dissociation, Dalenberg et al., 2012). Importantly the results indicate that a unique link exists between trauma and dissociation beyond the contribution of general psychopathology and parental dysfunctions. Moreover, different patterns emerged for non-taxon dissociation and pathological dissociation. Non-taxon dissociation correlated solely with childhood trauma when parental dysfunctions and general psychopathology were controlled. In contrast, the interaction between childhood and adulthood trauma plays a more important role than childhood trauma in explaining the variances of pathological dissociation. The first unresolved issue in the literature relates to the role of parental dysfunctions in dissociation. Using a dimensional approach to measure parental behaviors (Locke and Prinz, 2002), our results showed that both indifference and over-control are correlated with non-taxon and pathological dissociation. However, both aspects of parental dysfunctions were associated with general psychopathology as well, and the link between parental dysfunctions and dissociation became non-significant when general psychopathology was controlled. Parental dysfunctions may not be a specific determinant of dissociation, supporting the idea that parental dysfunctions may be non-specific risk factors for psychopathology (Gladstone and Parker, 2005).
It should be noted that parental dysfunctions and relational trauma may overlap (Bousha and Twentyman, 1984) in emotional abuse, as revealed by the mild and moderate correlations between the measures of the MOPS and the BBTS. It is important for future research to determine which component of childhood maltreatments not measured in parental dysfunctions leads to dissociation. As revealed by the significant effects of high-level betrayal on dissociation, conflicts in attachment may play a central role (Freyd, 1994). These findings are consistent with the view that dissociation may represent a drastically incoherent and incompatible representation of self that results from abusive relationships with significant others. Cumulative exposure to potentially traumatizing events may maintain a pathological organization of personality inscribed in early disorganized attachment (Liotti, 1999). It is for future investigation to clarify whether a unique relationship exists between dissociation and conflicts in attachment (Lyons-Ruth et al., 2006). The second and third unresolved issues in the literature regard the relationship between trauma at different time periods and two types of dissociation. The results showed that non-taxon dissociation was primarily a contribution of childhood trauma. In contrast, the effect of childhood trauma on pathological dissociation became non-significant when childhood trauma, adulthood trauma, and their interaction were entered into a multiple regression model. This finding supports the distinction between non-taxon dissociation and pathological dissociation (Waller et al., 1996; Nijenhuis and van der Hart, 2011). Non-taxon dissociation may reflect a dissociation tendency that is related to childhood trauma, and this dissociation tendency may be the base for the development of pathological dissociation under cumulative traumatization. The finding that the interactive model increased the amount of explained variance of pathological dissociation supports our hypothesis. Our result is inconsistent with the view that a unique link between trauma and pathological dissociation may not exist (Merckelbach and Muris, 2001; Lynn et al., 2014). The interaction suggests that adulthood trauma may reactivate the morbid effect of childhood trauma on the emergence of pathological dissociation. Alternatively, childhood trauma that occurs during stress-sensitive periods of development may lead to a psychophysiological vulnerability for later stressors and subsequent psychopathology (Heim et al., 2010; Heim and Binder, 2012). Childhood trauma can contribute synergically with adulthood trauma to fuel the development of pathological dissociation. The trauma hypothesis that focuses on repeated childhood trauma should incorporate the important role of cumulative traumatization in the emergence of pathological dissociation. Some weaknesses of the study should be noted. Firstly, the cross-sectional nature of this study restricts any attempt to identify the causal relationship between trauma and dissociation. It is possible that pathological dissociation is an antecedent rather than a consequence of successive exposures to potentially traumatizing events into adulthood. Dissociative individuals may not learn trauma-related cues from previously adverse experiences (EbnerPriemer et al., 2009) or may have reduced socio-cognitive capacity and be unable to interpret a social or affect-charged situation accurately (DePrince, 2005). As a result, they subsequently cannot detect potential risks or protect themselves from harm. Secondly, due to the retrospective nature of the self-report, the veracity of the reported parenting behavior and potentially traumatizing events may be questionable. Few studies examine this possibility, and it is a question for further investigation. Yet, acceptable reliability and validity were noted for the retrospective report of parental style and potential traumatizing events (Brewin et al., 1996; Wilhelm et al., 2005). Two clinical studies also demonstrated that the trauma memory reported by dissociative individuals can be corroborated to a certain degree (Chu et al., 1999; Coons, 1994).
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Thirdly, there remains a debate on the dimensions of pathological dissociation. While some researchers consider amnesia, reflecting a disturbance of deliberately recollecting autobiographical memory, to be the hallmark of pathological dissociation (Putnam, 1997), others claim that the fragmented subjective sense of self is also vital (Nijenhuis and Van der Hart, 2011). Amnesia, but not identity-related items, is included in the TDS. One should be cautious about generalizing our results to identity-related dissociation. Further research is required to uncover the complex relationship between parental dysfunctions, traumatizing experiences, and different types of dissociation.
5. Conclusion Supporting the trauma hypothesis of dissociation, an intertwined association between trauma and dissociation was found in a clinical sample of acute psychiatric inpatients. The association remained significant when the effects of perceived parental dysfunctions and general psychopathology were controlled, excluding the potential confounding effects from these two covariates. More importantly, the results showed that the interaction between childhood trauma and adulthood trauma contributed to pathological dissociation whereas non-taxon dissociation was primarily accounted for by childhood trauma. The results not only support the importance of distinguishing pathological dissociation from non-taxon dissociation but also the importance of cumulative traumatization in the emergence of pathological dissociation. The cumulative effect of traumatizing events from childhood to adulthood and the two types of dissociation should be considered (i.e., non-taxon and pathological) in future studies on the pathogenetic trajectory of dissociative pathology. 1. For the psychometric properties of the Chinese TDS in nonclinical samples, the internal consistency indexed by Cronbach's alpha is 0.91 (N ¼445), the criterion-related validity indexed by Pearson's correlation coefficient with the DES is 0.60 (N ¼445), and a six-week test–retest reliability using Pearson's correlation coefficient is 0.80 (N ¼77). 2. The pattern of results of the following correlation and regression analyses remains the same when items with cross loadings on both factors were removed in the analysis. 3. To ascertain the potential effect of multi-colinearity on estimation, another set of hierarchical regression models was constructed using the residual scores of each preceding model to examine the effect of adding a new variable. The results remained the same as those using standardized raw scores.
Disclosures and acknowledgments All of the authors report that they have no competing interests. The preparation of this manuscript was supported by a start-up grant from The Chinese University of Hong Kong to CDC and a grant from the National Science Council to YYY (NSC 102-2420-H002-009-MY2). Correspondence can be sent to CDC or YYY. CDC is now at The Chinese University of Hong Kong, [email protected]. edu.hk. YYY is at National Taiwan University, [email protected]. We thank Bernet Elzinga for her comments on an early version of this manuscript. We thank Chen-Chung Liu, Ming-Hsien Hsieh, Hsian-Yuan Lin, Chih-Lin Chiang, Shao-Chien Chen, Chi-Te Lee, Chun-Yuan Chen, Chan-Hen Tsai, Chia-Yin Kuo, Wei-Shih Liu, WeiChih Kao, En-Nie Du, and Chien-Heng Lin for their assistance in participant recruitment and case consultation. We also thank the patients for their participation in this study.
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