Dissociative symptoms in patients with schizophrenia

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Comprehensive Psychiatry 53 (2012) 364 – 371 www.elsevier.com/locate/comppsych

Dissociative symptoms in patients with schizophrenia: relationships with childhood trauma and psychotic symptoms Ingo Schäfera,⁎, Helen L. Fisherb , Volkmar Aderholdc , Barbara Hubera , Liv Hoffmann-Langera , Dietmar Golksa , Anne Karowa , Colin Rossd , John Reade , Timo Harfstf a

Department of Psychiatry and Psychotherapy, University Medical Centre Hamburg-Eppendorf, 20246 Hamburg, Germany MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, SE5 8AF London, UK c Institute for Social Psychiatry, Ernst-Moritz-Arndt University, 17487 Greifswald, Germany d The Colin A. Ross Institute for Psychological Trauma, Richardson, TX 75080, USA e Psychology Department, The University of Auckland, Auckland 1142, New Zealand f German Chamber of Psychotherapists, 10179 Berlin, Germany

b

Abstract Objective: This study sought to examine the stability of dissociative symptoms in patients with schizophrenia spectrum disorders as well as relationships between psychotic symptoms, childhood trauma, and dissociation. Method: One hundred forty-five patients with schizophrenia spectrum disorders (72% schizophrenia, 67% men) were examined at admission to inpatient treatment and 3 weeks later using the Positive and Negative Syndrome Scale, the Childhood Trauma Questionnaire, and the Dissociative Experiences Scale. Results: Dissociative symptoms significantly decreased over time (mean, 19.2 vs 14.1; P b .001). The best predictor of dissociative symptoms at admission was the Positive and Negative Syndrome Scale positive subscale (Finc 3,64 = 3.66, P = .017), whereas childhood sexual abuse best predicted dissociation when patients were stabilized (Finc 10,80 = 2.00, P = .044). Conclusion: Dissociative symptoms in patients with schizophrenia spectrum disorders are related to childhood trauma. Dissociation seems to be state dependent in this diagnostic group. Moreover, diagnostic interviews, in addition to the Dissociative Experiences Scale, should be considered to avoid measurement artifacts. © 2012 Elsevier Inc. All rights reserved.

1. Introduction Since Bleuler's [1] original conception of schizophrenia as a “splitting” of the psyche, there has been a consistent interest in dissociative phenomena in patients diagnosed with schizophrenia and other psychotic syndromes (eg, [2-4]). However, despite the high rate of traumatic experiences in patients with psychotic disorders [5,6], relatively few studies have focused on potential links between traumatic experiences and dissociation in this group. Most of the existing findings support such a relationship. For instance, in a study by Goff et al [7] among 61 patients with chronic psychotic disorders, participants with a history of childhood physical

⁎ Corresponding author. Tel.: +49 40 7410 59290; fax: +49 40 7410 55545. E-mail address: [email protected] (I. Schäfer). 0010-440X/$ – see front matter © 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.comppsych.2011.05.010

and/or sexual abuse (43% of the overall sample) reported significantly more dissociative symptoms than patients without abuse experiences. Similar relationships between sexual or physical abuse and dissociation have been reported by other studies [8-10] including a first episode sample [11]. Studies that also included other forms of childhood trauma, such as emotional abuse and neglect, observed the strongest relationships between dissociative symptoms and these 2 forms of early trauma [12-14], a finding also reported for other diagnostic groups [15,16]. The level of dissociative symptoms reported for patients with schizophrenia spectrum disorders varies substantially. In the studies that used the “Dissociative Experiences Scale” (DES) [17], the reported mean scores range between 10 and 30. For example, Modestin et al [18] reported the mean DES score of outpatients with schizophrenia spectrum disorders in remission to be 9.9, whereas Ross and Keyes [10] found that 60% of their schizophrenic patients had DES scores of 25 or

I. Schäfer et al. / Comprehensive Psychiatry 53 (2012) 364–371

above with a mean of 28.5. These divergent figures call for an explanation. Obviously, the stage of the disorder seems to play an important role. Investigations including schizophrenic patients in remission generally reported lower DES mean scores ranging between 9.9 and 15.3 [18-20]. Studies including patients irrespective of the stage of their illness consistently find higher mean DES scores between 15.7 and 28.5 [8,10,21-24]. To date, only 1 study examined patients with schizophrenia spectrum disorders in different stages of their illness [13]. In this study, 30 female patients were examined at admission to an inpatient unit for patients with psychotic disorders and several weeks later when they were stabilized. A significant decrease of the DES mean score was found from 21.0 at admission to 11.9 at the second interview. At admission, significant correlations between dissociative symptoms and the subscales “emotional abuse” and “physical neglect” of the Childhood Trauma Questionnaire (CTQ) [25] were observed. However, only the relationship with emotional abuse remained significant when patients were stabilized, suggesting that psychotic symptoms might mediate the relationship between trauma and dissociation in patients with schizophrenia. Other studies examined more directly relationships between dissociation and psychotic symptoms. In a study of 27 patients with schizophrenia spectrum disorders, Spitzer et al [24] found a close association between dissociative symptoms and positive symptoms as measured by the Positive and Negative Syndrome Scale (PANSS) [26]. Patients with a predominance of positive symptoms had significantly higher DES mean scores as compared with patients with a predominance of negative symptoms (mean, 21.1 vs 9.2). Delusions and hallucinations were strongly and positively related to the DES total score and most subscales of the DES, whereas there were very few significant correlations between dissociation and other positive psychotic symptoms. Likewise, Ross and Keyes [10] and Kilcommons and Morrison [27] indicated that dissociation is associated with positive schizophrenic features, particularly hallucinations. Other studies found significant relationships between dissociation and both positive and negative symptoms of schizophrenia [9]. Dorahy et al [28] compared the quality of auditory hallucinations in 18 schizophrenic patients without child maltreatment, 16 schizophrenic patients with child maltreatment, and 29 patients with dissociative identity disorder. The 3 groups incrementally increased on child maltreatment and pathological dissociation, as measured by the “taxon score” of the DES (DES-T) [29]. Dissociation predicted several characteristics of voice hearing, again, suggesting potential relationships between these 2 domains of symptoms. Taken together, the existing findings suggest that dissociative symptoms are related to childhood trauma in patients with schizophrenia spectrum disorders, but the potentially mediating role of the phase of the illness and acute psychotic symptoms on this relationship remains

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unclear. In the present study, we aimed to extend our previous findings [13] by examining relationships between childhood trauma, dissociation, and psychotic symptoms in a larger group of patients with schizophrenia spectrum disorders of both sexes after admission and in a more stable phase of their illness. Our hypotheses were (1) that DES scores would decrease significantly between admission to inpatient treatment and a second interview several weeks later; (2) that childhood abuse would be most strongly related to dissociative symptoms when patients were stabilized; and (3) that positive symptoms, as measured by the PANSS, would be significantly related to dissociative symptoms at the first interview but not when patients were stabilized. 2. Materials and methods 2.1. Participants The participants were patients of a specialized ward for psychotic disorders at the University Medical Center Hamburg-Eppendorf, Hamburg, Germany. Inclusion criteria were diagnosis of a schizophrenia spectrum disorder (International Statistical Classification of Diseases, 10th Revision, F20-F29), aged between 18 and 65 years, and sufficient German language abilities. Exclusion criteria were a very brief admission (≤3 days) and clinical states leading to potential risks in the case of participation (eg, persisting acute suicidality). All subjects gave written consent after being informed on the purpose and procedures of the study. The study was approved by the responsible ethics committee (State Chamber of Physicians, Hamburg, Germany). Of the 283 consecutive patients who met the inclusion criteria, 178 (63%) agreed to participate in the study. Of these, 20 could not be examined because they left the ward too soon after the minimum length of stay defined in the study protocol or because they did not show up to the interviews despite continuing efforts to make this possible. During the assessment of childhood trauma, 2 patients decided not to complete the interview because they became too upset. In the case of another 2 patients, the interviewer made this decision. The data of another 9 patients were later excluded from the analysis because of inconsistent information given in the interview. The final sample included 145 caucasian patients (51%) comprising 97 men (67%) with a mean age of 34 years (SD, 11.5). Most (104, or 72%) had a diagnosis of schizophrenia, 32 (22%) had schizoaffective disorder, and 9 (6%) had other schizophrenia spectrum disorders (eg, schizophreniform or delusional disorder). The mean duration of illness was 7.8 years (SD, 9.7 years). In 31% of the patients, the onset of the illness was within the year before admission; in 25%, the duration of illness was more than 1 but not more than 5 years; and in 44%, the duration of the illness was more than 5 years.

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2.2. Assessment instruments Diagnoses were made using the Mini International Neuropsychiatric Interview [30] and the psychosis section of the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition [31]. Psychotic symptoms were measured using the PANSS [26] at admission (T0) and again at the main interview (T1) by trained raters blind to trauma history. The main interview took place when the patients were considered sufficiently stable by the therapeutic team (mean, 20.9 days after admission; SD, 13.2). At this time, PANSS scores had significantly decreased (mean, 80.3; SD, 17.1 vs mean, 66.1; SD, 14.3; P b .001). At both time points, T0 and T1, patients were asked to complete a German version of the DES [17]. This reliable and internally consistent self-report questionnaire is the most widely used instrument for dissociative symptoms in clinical samples. It contains items referring to amnesia, depersonalization, derealization, absorption, and identity alteration and comprises 3 subscales (absorption, depersonalization, and amnesia). The German version of the DES yields good to excellent statistical parameters similar to the original version [32]. The 8-item DES-T score, a subscale from the DES comprising the items 3, 5, 7, 8, 12, 13, 22, and 27 was also computed as a measure of “pathological dissociation” [29]. The main analysis was based on the DES at T1. The DES total score at T1 showed high internal consistency in the current sample (Cronbach α = .93). Good internal consistency was also found for DES subscales and the DES-T (amnesia, Cronbach α = .83; absorption, α = .87; depersonalization, α = .77; DES-T, α = .80). The type and severity of childhood trauma were assessed at T1 using the CTQ [25]. This 28-item selfreport questionnaire assesses not only physical and sexual abuse but also emotional neglect, emotional abuse, and physical neglect. Items are rated on a 5-point scale (1, never true to 5, very often true), with scores of each subscale ranging from 5 to 25. Strong psychometric properties have been demonstrated for the CTQ in clinical as well as community samples [33]. The scores for each subscale were also categorized as proposed by the authors of the CTQ (“none or minimal,” “low to moderate,” “moderate to severe,” and “severe to extreme”; [25]).

transformation of DES total score and CTQ subscales to reduce skewness and number of outliers and to improve normality, linearity and homoscedasticity of residuals. Logarithmic transformations were used on the CTQ subscales sexual abuse and physical abuse; square root transformations were used on the DES total score and all other CTQ subscales. With the use of a Mahalanobis distance, no outliers among the cases were found. SPSS version 16.0 (SPSS Inc, Chicago, IL) was used for all analyses, and the level of significance was set at P = .05 for all tests.

3. Results 3.1. Levels of childhood trauma, dissociation, and psychotic symptoms When patients were stabilized, they reported substantial rates of childhood traumatizing events (CTQ total score: mean, 49.4; SD, 15.0; sexual abuse: mean, 7.0; SD, 4.1; physical abuse: mean, 7.4; SD, 3.7; physical neglect: mean, 9.6; SD, 3.4; emotional abuse: mean, 11.5; SD, 5.1; emotional neglect: mean, 13.9; SD, 4.9; n = 138). Rates of each form of childhood trauma according to degree of severity are presented in Table 1. Emotional abuse and neglect (both emotional and physical) were the most frequently reported forms of trauma at severe levels (24.6%, 23.2%, and 21.7%, respectively). Severe sexual abuse (13.0%) and physical abuse (10.1%) were less common. Levels of dissociation as measured with the DES and psychotic symptoms assessed with the PANSS are displayed in Table 2. The mean scores on all subscales of the DES and PANSS were lower at T1 than at T0. Analysis of variance with repeated measures demonstrated a significant decrease of the DES total score over time with a medium effect size (F1,82 = 18.1, P b .001, partial η2 = 0.181). 3.2. Associations between childhood trauma and dissociative symptoms At T0, the sexual, physical, and emotional abuse subscales of the CTQ showed significant correlations with the DES total score (ρ = 0.280, P b .01; ρ = 0.223, P b .05; and ρ = 0.205, P b .05, respectively). Sexual abuse was also

2.3. Statistical analysis

Table 1 Frequency of different forms of childhood abuse (CTQ categories [25])

Analysis of variance with repeated measures was used to examine the change of the PANSS and DES scores over time. Associations between dissociative symptoms and childhood traumatic experiences were analyzed by the Spearman ρ correlation coefficient. Sequential multiple regression was performed between the DES total score as the dependent variable and sex and age (step 1), PANSS positive and negative symptoms and general psychopathology (step 2), and the continuous CTQ subscale scores as independent variables (step 3). Results of evaluation of assumptions led to

CTQ subscales

Clinical categories None or minimal

Sexual abuse Physical abuse Physical neglect Emotional abuse Emotional neglect n = 138.

Low to moderate

Moderate to severe

Severe to extreme

n (%)

n (%)

n (%)

n (%)

96 93 49 53 29

10 (7.2) 16 (11.6) 21 (15.2) 36 (26.1) 45 (32.6)

14 (10.1) 14 (10.1) 38 (27.5) 15 (10.9) 32 (23.2)

18 15 30 34 32

(69.6) (67.4) (35.5) (38.4) (21.0)

(13.0) (10.9) (21.7) (24.6) (23.2)

I. Schäfer et al. / Comprehensive Psychiatry 53 (2012) 364–371 Table 2 Dissociative Experiences Scale/PANSS scores at T0 and T1 F

P

η2p

8.9 (11.0) 19.2 (14.2) 13.3 (14.6) 11.1 (12.4) 14.1 (12.0)

11.6 16.7 15.6 14.5 18.1

b.001 b.001 b.001 b.001 b.001

0.124 0.169 0.160 0.151 0.181

14.3 (4.3) 17.5 (5.1) 34.3 (7.8) 66.1 (14.3)

82.0 36.2 82.2 94.5

b.001 b.001 b.001 b.001

0.509 0.314 0.510 0.545

T0

T1

Mean (SD)

Mean (SD)

13.3 (14.5) 25.2 (16.6) 18.1 (18.3) 15.1 (15.0) 19.2 (15.0) 18.1 (5.4) 20.5 (6.4) 41.8 (9.4) 80.3 (17.1)

a

DES Amnesia Absorption Depersonalization DES-T Total score PANSSb Positive score Negative score General score Total score

F indicates analysis of variance statistic; η2p, partial η2. a T0 and T1; n = 83. b T0 and T1; n = 80.

correlated with the absorption, depersonalization, and amnesia subscales of the DES (ρ = 0.257, P b .05; ρ = 0.224, P b .05; and ρ = 0.297, P b .01, respectively). Moreover, significant correlations were observed between emotional and physical abuse and absorption (ρ = 0.253, P b .05 and ρ = 0.245, P b .05, respectively) as well as between physical neglect and the amnesia subscale of the DES (ρ = 0.217, P b .05, Table 3). At T1, when patients were stabilized, a different pattern became apparent. Only the sexual and emotional abuse subscales of the CTQ were significantly correlated with the DES total score (ρ = 0.264, P b .01 and ρ = 0.234, P b .05, respectively). Both of these forms of abuse were also correlated with the absorption and amnesia subscales of the DES. Moreover, significant correlations were observed between physical abuse and neglect and the amnesia subscale of the DES (ρ = 0.224, P b .05 and ρ = 0.222, P b .05, respectively). 3.3. Prediction of dissociative symptoms In a sequential linear regression model, addition of the PANSS subscales at T0 significantly improved the prediction

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of dissociation at admission (Finc 3,64 = 3.66, P = .017), with the PANSS positive subscale being the only significant predictor in the model. Addition of CTQ subscales in step 3 of the model did not result in a significant increment in R2 (Finc 5,59 = 1.14, P = .348), and PANSS positive symptoms remained the only significant predictor of dissociation at this time (Table 4). In a corresponding model at T1, sexual abuse was the single best predictor of dissociative symptoms. Table 5 displays the unstandardized regression coefficients (B) and intercept, the standardized regression coefficients (β), as well as R and R2 at the end of each step. Only after step 3, with all independent variables in the equation, R was significantly different from 0 (R = 0.447, F10,80 = 2.00, P = .044). Addition of psychopathology measured by PANSS subscales in step 2 did not reliably improve R2 (Finc 3,85 = 2.11, P = .105). The addition of the CTQ subscales in step 3 resulted in a significant increment in R2 (Finc 5,80 = 2.522, P = .036), with sexual abuse being the only significant predictor of dissociation in the final model.

4. Discussion In the present study, we observed a significant decrease of self-reported dissociation over time in a larger sample of patients with schizophrenia spectrum disorders, confirming our previous findings [13]. Moreover, positive symptoms were the best predictor of dissociation at admission, suggesting close relationships between both symptom domains. When patients were stabilized, childhood sexual abuse was the best predictor of dissociative symptoms, whereas no relationship between dissociation and psychotic symptoms existed now. The tendency to experience dissociative symptoms is considered to be a rather stable trait [17]. In nonpsychotic populations, the DES usually produces scores that are stable over time, with test-retest reliability coefficients ranging from 0.79 to 0.96 [34]. Therefore, the changing levels of dissociative symptoms reported by our sample merit some attention.

Table 3 Relationships between childhood trauma (CTQ) and dissociation (DES) at T0 and T1 CTQ (subscales)

DES (subscales) Absorption

Sexual abuse Physical abuse Physical neglect Emotional abuse Emotional neglect Total score

Depersonalization

Amnesia

DES-T score

T0

T1

T0

T1

T0

T1

T0

.257⁎ .245⁎ .124 .253⁎ .089 .250⁎

.260⁎⁎ .150 .107 .256⁎⁎ .032 .188⁎⁎

.224⁎ .188 .171 .125 .024 .077

.132⁎ .093 .052 .147⁎ −.025 .186⁎

.297⁎⁎ .189 .217⁎ .183 .148 .267⁎⁎

.321⁎⁎ .224⁎⁎ .222⁎ .239⁎⁎ .077 .275⁎⁎

.229⁎ .144 .175 .161 .121 .216⁎

T0, n = 93; T1, n = 118. Spearman's rank correlation coefficient ρ (bivariate). ⁎ P b .05. ⁎⁎ P b .01.

Total score

T1

T0

T1

.140 .074 .081 .159⁎ .018 .104

.280⁎⁎ .223⁎ .176 .205⁎ .090 .251⁎

.264⁎⁎ .169 .129 .234⁎ .032 .193⁎

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Table 4 Sequential regression of sociodemographic, psychopathology, and trauma variables on dissociation at T0 (square root of DES total score) Model 1

2

3

B (95% CI) Constant Sex Age Constant Sex Age PANSS positive symptoms (T0) PANSS negative symptoms (T0) PANSS general symptoms (T0) Constant Sex Age PANSS positive symptoms (T0) PANSS negative symptoms (T0) PANSS general symptoms (T0) CTQ sexual abuse CTQ physical abuse CTQ physical neglect CTQ emotional neglect CTQ emotional abuse

4.41 (2.39-6.43) 0.00 (−0.83 to 0.83) −0.04 (−0.39 to 0.31) 3.12 (0.59-5.65) −0.32 (−1.16 to 0.51) −0.01 (−0.04 to 0.02) 0.12 (0.04-0.19) 0.05 (−0.03 to 0.12) −0.03 (−0.09 to 0.03) 1.13 (−2.95 to 5.22) −0.18 (−1.09 to 0.73) −0.02 (−0.04 to 0.03) 0.11 (0.03-0.19) 0.04 (−0.04 to 0.12) −0.02 (−0.08 to 0.04) 0.88 (−0.23 to 2.00) 0.24 (−1.06 to 1.55) 0.36 (−0.48 to 1.19) −0.32 (−1.01 to 0.37) −0.11 (−0.83 to 0.60)

β .000 −.025 −.097 −.002 .410 −.187 .231 −.054 −.002 .383 .162 −.120 .227 .058 .120 −.122 −.049

t

P

R for model

R2 for model

4,35 0.00 −0.20 2.46 −0.77 −0.02 3.14 1.21 −1.13 0.55 −0.394 −1.28 2.91 1.02 −0.68 1.59 0.37 0.85 −0.93 −0.32

.000 .999 .839 .016 .443 .985 .003 .229 .265 .581 .695 .899 .005 .311 .502 .116 .710 .397 .355 .754

0.025

0.001

0.383

0.147

0.471

0.222

B indicates β; β, standardized β coefficient; CI, confidence interval; t, test statistic; R, correlation coefficient; R2, proportion of variance explained by the model.

One possible explanation of the varying scores is the considerable overlap between dissociative phenomena and psychotic symptoms in clinical samples. The most consistent relationships have been reported between the depersonalization/derealization subscale of the DES and positive symptoms, especially delusions and hallucinations [24,27]. However, all 6 items of the depersonalization/ derealization subscale concern perceptual experiences, including hearing voices. Although some authors suggested that the relationship between this subscale and experiencing hallucinations might reflect a higher tendency of people responding to trauma with dissociation to experience hallucinations [27], it could at least partly be the result of shared item content. Moreover, delusional patients can have problems in understanding the items of the DES, and it can be difficult to distinguish dissociative phenomena from delusions [35]. These issues emphasize that more attention has to be paid to methodological issues when dissociation is assessed in psychotic patients and that diagnostic interviews should be more systematically used to confirm the findings of self-rating instruments. Another possible explanation for the relationship between psychotic and dissociative symptoms in the acute phase of the illness is an interaction between both types of psychopathology. It has been suggested that severe dissociation or symptoms of posttraumatic stress disorder may produce psychotic symptoms or could be a mediating factor in their development (eg, [4,36]). Allen et al [37] emphasized the special role of dissociative detachment in this context. They suggested that dissociative detachment “undermines the individual's grounding in the outer world, thereby hampering reality-testing and rendering the individual with posttraumatic symptoms vulnerable to the nightmarish

inner world.” Other authors suggest an inverse relationship. For instance, Giese et al [38] proposed that dissociation might arise as a defense against the “disorganizing pressure of abnormal affect” in patients with psychotic mood disorders or that psychotic symptoms might lower the threshold for the expression of dissociation in patients predisposed to this phenomenon because of early trauma. They referred to cases where even severe dissociative symptoms, such as alternate personalities and amnesic episodes, disappeared when the psychotic disorder was successfully treated (eg, [39]). Similar interaction models have also been proposed for posttraumatic stress disorder and the symptoms of severe mental illness [9,40]. Finally, both psychotic and dissociative manifestations could be an independent result of reactivated traumatic memories in some patients. The relationship between early trauma and dissociation in patients with psychosis is in line with similar findings for many other diagnostic groups (for review, see [41]). In our sample, such relationships became stronger when patients were stabilized, again, suggesting a more reliable assessment of dissociation now. As in our previous study [13], emotional abuse was among the forms of childhood trauma most strongly related to dissociative symptoms. The strongest relationship, however, was with childhood sexual abuse. Interestingly, Sar et al [9] recently described 2 clusters of schizophrenic patients with dissociative symptoms, 1 being more strongly related to childhood sexual abuse and the other to childhood emotional abuse. Furthermore, from a phemenological point of view, it is likely that different subgroups of patients with high levels of dissociation existed within our sample. For instance, a considerable comorbidity of dissociative disorders has


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Table 5 Sequential regression of sociodemographic, psychopathology, and trauma variables on dissociation at T1 (square root of DES total score) Model 1

2

3

B (95% CI) Constant Sex Age Constant Sex Age PANSS positive symptoms (T1) PANSS negative symptoms (T1) PANSS general symptoms (T1) Constant Sex Age PANSS positive symptoms (T1) PANSS negative symptoms (T1) PANSS general symptoms (T1) CTQ sexual abuse CTQ physical abuse CTQ physical neglect CTQ emotional neglect CTQ emotional abuse

3.84 (2.36-5.32) 0.67 (−0.57 to 0.70) −0.01 (−0.04 to 0.02) 2.69 (0.85-4.53) 0.01 (−0.66 to 0.65) −0.01 (−0.04 to 0.02) 0.06 (−0.02 to 0.13) −0.05 (−0.14 to 0.04) 0.04 (−0.02 to 0.10) 0.76 (−2.45 to 3.96) 0.19 (−0.49 to 0.86) −0.01 (−0.03 to 0.02) 0.05 (−0.02 to 0.12) −0.03 (−0.12 to 0.06) 0.04 (−0.02 to 0.10) 0.88 (0.01-1.75) −0.42 (−1.54 to 0.70) −0.27 (−0.98 to 0.43) −0.13 (−0.67 to 0.42) 0.56 (−0.02 to 1.14)

been described for patients with schizophrenia spectrum disorders [10] as well as trauma-related subtypes of psychosis characterized by differences in course and symptoms [42-44]. It thus seems likely that patients reporting dissociative experiences represent a heterogeneous group with differences in terms of phenomenology and potentially also the mechanisms involved in the development of disorder. Although none of the existing studies had a sample size and methodology that would have made this possible, future studies should aim at identifying different subgroups of patients with a relevant amount of dissociative symptoms among patients with schizophrenia spectrum disorders. A limitation of our findings was the sampling strategy used. All patients were recruited on an open ward for patients with psychotic disorders, and many had only moderately severe psychotic syndromes. The inclusion of more severely ill patients might have led to different findings. However, in view of the existing findings on relationships between stage of the illness and dissociative symptoms (eg, [10,23,24]), it seems likely that relationships between dissociation and psychotic symptoms at admission would have been even stronger. In several cases, patients with a severe trauma history had to be excluded because the interviews were too upsetting for them. The exclusion of patients with very brief admissions, many of whom were “revolving door” patients and potentially more likely to have experienced early trauma, may have further decreased the proportion of traumatized patients in our sample. Again, the reported relationships, especially the relationship between trauma and dissociation, might have been even stronger if a higher percentage of these patients could have been examined. On the other hand, it cannot be excluded that childhood trauma would also have been a significant

β .023 −.065 .003 −.075 .183 −.201 .231 .063 −.044 .153 −.122 .212 .249 −.113 −.109 −.057 .284

t

P

R for model

R2 for model

5.16 0.21 −0.61 2.91 −0.03 −0.71 1.58 −1.20 1.34 0.47 0.56 −0.43 1.37 −0.74 1.24 2.02 −0.74 −0.77 −0.46 1.92

.000 .833 .542 .001 .980 .480 .118 .235 .184 .640 .579 .671 .176 .464 .219 .047 .461 .447 .646 .059

0.071

0.005

0.272

0.074

0.447

0.200

predictor of dissociation already at admission. In addition, this study relied on retrospective self-reports of childhood trauma, the accuracy of which has been called into question especially among patients experiencing psychosis [45]. Nevertheless, disclosures of childhood abuse by individuals with psychotic disorders have repeatedly been shown to be reliable [46] most recently by Fisher et al [47] who, importantly, also found that the likelihood of disclosure is unrelated to severity of symptoms. In the current study, patients only completed the CTQ once their symptoms had significantly reduced; thus, minimizing the possible impact on recall. Moreover, the rates of childhood trauma reported by patients in the current study are similar to those found by other studies using this instrument (eg, [14]). Another shortcoming of our study is that somatoform manifestations of dissociative processes have not been considered. Future studies should include appropriate measures to also cover this type of dissociative symptoms (eg, the Somatoform Dissociation Questionnaire; [48]). In conclusion, our findings indicate that dissociative symptoms in patients with schizophrenia spectrum disorders are state dependent. When dissociative symptoms are examined in more acute phases of the illness, the use of diagnostic interviews in addition to the DES should be considered to avoid measurement artifacts. Moreover, somatoform manifestations of dissociative processes should be considered. In patients with definite dissociative symptoms, it remains to be clarified whether they represent a superimposed phenomenon, which, nevertheless, might interact with other symptom domains or, if a more basic relationship exists, with psychotic symptoms. One rather obvious clinical implication is that all clients with psychotic symptoms/diagnoses should be asked about childhood abuse [49], which, research demonstrates, is not

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yet happening [5,45,47,49], and patients with posttraumatic syndromes should be offered appropriate psychological therapies that have been made available for this group in recent years (eg, [50-53]). Acknowledgment This study was funded by the Werner Otto Foundation, Hamburg. HLF is supported by a postdoctoral fellowship from the UK Medical Research Council and the Economic and Social Research Council. The authors thank Nele Rehder, Svenja Ehlers, Sybille Gussmann, Irina Leichsenring, and Marcus Albert for their participation in collecting the data. References [1] Bleuler E. Dementia praecox oder die Gruppe der Schizophrenien. Leipzig: Deuticke; 1911. [2] Saperstein JL. On the phenomena of depersonalization. J Nerv Ment Dis 1949;110:236-51. [3] Sedman G, Kenna JC. Depersonalization and mood changes in schizophrenia. Br J Psychiatry 1963;109:669-73. [4] Steingard S, Frankel FH. Dissociation and psychotic symptoms. Am J Psychiatry 1985;142(8):953. [5] Read J, Van Os J, Morrison AP, Ross CA. Childhood trauma, psychosis and schizophrenia: a literature review with theoretical and clinical implications. Acta Psychiatr Scand 2005;112(5):330-50. [6] Morgan C, Fisher H. Environment and schizophrenia: environmental factors in schizophrenia: childhood trauma—a critical review. Schizophr Bull 2007;33(1):3-10. [7] Goff DC, Brotman AW, Kindlon D, Waites M, Amico E. Self-reports of childhood abuse in chronically psychotic patients. Psychiatry Res 1991;37(1):73-80. [8] Bob P, Glaslova K, Susta M, Jasova D, Raboch J. Traumatic dissociation, epileptic-like phenomena, and schizophrenia. Neuroendocrinology Letters 2006;27(3):321-6. [9] Sar V, Taycan O, Bolat N, Ozmen M, Duran A, Ozturk E, et al. Childhood trauma and dissociation in schizophrenia. Psychopathology 2010;43(1):33-40. [10] Ross CA, Keyes B. Dissociation and schizophrenia. J Trauma Dissociation 2004;5(3):69-83. [11] Greenfield SF, Strakowski SM, Tohen M, Batson SC, Kolbrener ML. Childhood abuse in first-episode psychosis. Br J Psychiatry 1994; 164(6):831-4. [12] Holowka DW, King S, Saheb D, Pukall M, Brunet A. Childhood abuse and dissociative symptoms in adult schizophrenia. Schizophr Res 2003;60(1):87-90. [13] Schafer I, Harfst T, Aderhold V, Briken P, Lehmann M, Moritz S, et al. Childhood trauma and dissociation in female patients with schizophrenia spectrum disorders: an exploratory study. J Nerv Ment Dis 2006;194(2):135-8. [14] Vogel M, Spitzer C, Kuwert P, Moller B, Freyberger HJ, Grabe HJ. Association of childhood neglect with adult dissociation in schizophrenic inpatients. Psychopathology 2009;42(2):124-30. [15] Schafer I, Reininghaus U, Langeland W, Voss A, Zieger N, Haasen C, et al. Dissociative symptoms in alcohol-dependent patients: associations with childhood trauma and substance abuse characteristics. Compr Psychiatry 2007;48(6):539-45. [16] Simeon D, Guralnik O, Schmeidler J, Sirof B, Knutelska M. The role of childhood interpersonal trauma in depersonalization disorder. Am J Psychiatry 2001;158(7):1027-33.

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