DissociationinPsychiatricdisorders1.pdf
Dissociation in Psychiatric Disorders: A Meta-Analysis of Studies Using the Dissociative Experiences Scale Lisa Lyssenko, Dipl.-Psych., Christian Schmahl, Dr.med., Laura Bockhacker, Dr.med., Ruben Vonderlin, M.Sc., Martin Bohus, Dr.med., Nikolaus Kleindienst, Dr.rer.hum.biol.
Objective: Dissociation is a complex, ubiquitous construct in psychopathology. Symptoms of dissociation are present in a variety of mental disorders and have been connected to higher burden of illness and poorer treatment response, and not only in disorders with high levels of dissociation. This meta-analysis offers a systematic and evidence-based study of the prevalence and distribution of dissociation, as assessed by the Dissociative Experiences Scale, within different cat- egories of mental disorders, and it updates an earlier meta- analysis.
Method: More than 1,900 original publications were screened, and 216 were included in the meta-analysis, comprising 15,219 individuals in 19 diagnostic cate- gories.
Results: The largest mean dissociation scores were found in dissociative disorders (mean scores .35), followed by post- traumatic stress disorder, borderline personality disorder, and conversion disorder (mean scores .25). Somatic symptom disorder, substance-related and addictive disorders, feeding and eating disorders, schizophrenia, anxiety disorder, OCD, and most affective disorders also showed mean dissociation scores .15. Bipolar disorders yielded the lowest dissociation scores (mean score, 14.8).
Conclusions: The findings underline the importance of careful psychopathological assessment of dissociative symp- toms in the entire range of mental disorders.
Am J Psychiatry 2018; 175:37–46; doi: 10.1176/appi.ajp.2017.17010025
Dissociation is a ubiquitous construct in modern psychopa- thology. DSM-5 defines dissociation as “disruption of and/or discontinuity in the normal integration of consciousness, memory, identity, emotion, perception, body representation, motor control, and behavior” (1). The corresponding phe- nomena cover a range from relatively common experiences, suchasbeingcompletelyabsorbedbyabookormovie,tosevere states, such as not recognizing oneself in the mirror (2). More common experiences have often been linked to mild forms of absorption, that is, focusing on one aspect of experiences and blocking others (3). More severe dissociative experiences are reflected in the DSM-5 subtypes of dissociative disorders: dissociative amnesia describes the inability to recall autobio- graphical information; depersonalization/derealization disor- derscompriseexperiencesoffeelingdisconnectedorestranged from one’s body, thoughts,oremotionsand/or perceiving one’s surroundings as foggy, surreal, or visually distorted (1).
Beyond the disorders primarily characterized by disso- ciation, “transient, stress-related severe dissociative symp- toms” serve as a criterion for borderline personality disorder (1),andadissociativesubtypeofposttraumaticstressdisorder (PTSD) was introduced in DSM-5 (4). Less noted but equally important research has shown that dissociative features also
seem to play a role in the pathology of many other mental disorders, such as schizophrenia (5), eating disorders (6), panic disorders (7), affective disorders (8, 9), and obsessive- compulsive disorder (OCD) (10).
Dissociative symptoms in mental disorders are of high clinical relevance. They have been linked to maladaptive functioning and symptom severity in some disorders, such as executive functioning in borderline personality disorder (11), neuropsychological performance in depression (9), number of binge episodes in eating disorders (6), alexithymia in panic disorders (12), and anxiety and depression in OCD (13). Apart from a higher burden of illness, patients may also benefit less from psychotherapeutic interventions. Several studies have indicated that dissociative symptoms can serve as a predictor for nonresponse in psychotherapeutic treatments of PTSD (14–16), OCD (17–19), and panic disorders (20).
Transdiagnostically, the experience of dissociative symp- toms has been linked to acute or chronic stress (21). Neuro- biological findings suggest that dissociative phenomena are likelytodisruptinformationprocessing,learning,andmemory on various levels (22). Dissociation has been further linked to physiological processes such as sleep (23) and fluid intake (24), as well as to personality variables, such as fantasy
See related features: Editorial by Dr. Spiegel (p. 4) and Clinical Guidance (Table of Contents)
Am J Psychiatry 175:1, January 2018 ajp.psychiatryonline.org 37
ARTICLES
proneness and suggestibility (25). On a cognitive-emotional level, dissociation may be a learned automatic response to re- duce or avoid aversive emotional states (26, 27). As a secondary process, the experience of dissociation can induce stress itself because it not only disrupts neurocognitive functioning, but can also be perceivedas losing control (28). Recurrent dissociation may therefore reduce the individual’s confidence in reality monitoring ability, perceivedcontrol,and sense of self (29, 30), which in turn may result in a higher burden of disease.
The transdiagnostic evaluation of those mechanisms is im- peded by the fact that neurobiological studies have been mostly conducted in populations of patients who had experienced various traumas, often chronically and/or early in life (e.g., 31). Althoughthestatisticalassociationwasfoundtoberathersmallin some studies (27), several studies have pointed to a strong asso- ciation between trauma and dissociation (32–36). Thus, the ex- perience of trauma does not seem to be a conditio sine qua non for pathological dissociation. Studies covering a broader range of mental disorders could shed light on common mechanisms and enhance the development of transdiagnostic treatment modules to deal with dissociative symptoms. The meta-analysis we present hereaimstostimulatethislineofresearchbyprovidinganoverview oftheoccurrenceofdissociativesymptomsacrossmentaldisorders.
By far, the most commonly used psychometric instrument for the assessment of dissocia- tive experience is the Dissocia- tive Experiences Scale (DES) (2). The DES is a self-rating instrument comprising 28 items that build on the assumption of a “dissociative continuum” ranging from mild normative to severe pathological disso- ciation. Subjects are asked to make slashes on 100-mm lines to indicate where they fall onacontinuum for questions on experiences of amnesia, absorption, depersonalization, andderealization—forexample, “Some people have the experi- ence of driving a car and sud- denly realizing that they don’t remember what has happened during all or part of the trip. Mark the line to show what percentageoftimethishappens toyou”(2,p.733).Asthescoring procedure of the continuous scale was time consuming, a revised version of the scale, the Dissociative Experiences Scale–II (DES-II) (37) uses an 11-point Likert scale ranging from 0 to 100.
Studies on the psychometric properties of the scale have shown high validity and reliability for both versions, both in clinicalandnonclinicalpopulations(38–42).Thefirst,andsofar the only, comprehensive meta-analysis on the DES, by van IjzendoornandSchüngel(43),conductedin1996,showsamean Cronbach’s alpha of 0.93 in 16 studies, a high predictive validity concerning dissociative disorders and PTSD, as well as a high convergent validity with alternative measures of dissociation (mean Cohen’s d=1.82; N=5,916). While initial studies (e.g., 44) found a three-factor structure with the factors amnesia, ab- sorption, and depersonalization/derealization, the factorial structure of the DES remains controversial (41, 42, 45, 46).
Considering the high number of original publications on theDES(N.2,000),fewmeta-analyseshavebeenconducted. One meta-analysis on schizophrenia showed a large effect size comparing dissociation scores of patients (N=293) and healthy subjects (N=474) (g=20.86, 95% CI=21.13, 20.60), with trauma history being a potential mediator (5). Scalabrini et al. (47) compared the dissociation scores in borderline personality disorder with those in other mental disordersand found significantly elevated dissociative symptoms in patients withborderlinepersonalitydisordercomparedwithpatientswith all other disorders (N=2,035; d=0.54, p,0.01) but lower levels of
FIGURE 1. PRISMA Flow Diagram for a Meta-Analysis of Dissociation in Psychiatric Disorders Id
e n
ti fi
c a
ti o
n E
li g
ib il
it y
S c
re e
n in
g In
c lu
d e
d
Records identifi ed through database searching (PubMed,
PsycINFO, Web of Science, Academic Search Premier)
(N=3,492)
Excluded duplicates (N=1,585)
Full-text articles assessed for eligibility (N=1,247)
Articles eligible for review (N=221)
Excluded because <4 articles per diagnosis (N=5)
Records screened (N=1,907)
Records excluded at title or abstract screening (N=660)
Studies included (N=216)
Full-text articles excluded (N=1,026) – Healthy sample (N=296)
– No distinguishable diagnostic groups (N=149)
– No analysable DES score (N=142)
– Unpublished dissertations (N=109)
– No DES score (N=103)
– No DSM diagnosis (N=108)
– Other DES versions (N=27)
– Conference papers (N=23)
– Other reasons (N=69)
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DISSOCIATION IN PSYCHIATRIC DISORDERS
dissociation than in patients withPTSD(d=20.50,p,0.01) and dissociative disorders (d= 20.35, p,0.05). As noted, theonlycomprehensivemeta- analysis, by van Ijzendoorn and Schüngel (43), was pub- lished about 20 years ago and included 85 individual studies with about 6,000 patients. As expected, the highest scores for dissociation were found for dissociative disorders (mean= 35.3), followed by PTSD (mean=32.6), affective disor- ders (mean=19.4), schizophre- nia (mean=19.1), personality disorders (mean=16.6), eating disorders (mean=14.5), and anxiety disorders (mean=10.2). Comparison scores were cal- culated for healthy samples (mean=11.57) and students (mean=14.27). The authors conclude that “against the background of potential comor- bidity and undiscovered dissociation, the means for normals and nondissociative patients were remarkably similar” (43, p. 372).
Since the meta-analysis by van Ijzendoorn and Schüngel (43), dissociation has been studied in a range of mental disorders that had not been included, such as OCD (10) and substance abuse (48). Other research has shown that dis- sociation plays a role in diseases like panic disorders (7, 31), which showed surprisingly low mean dissociation scores in that first analysis. The goal of our meta-analysis is thus to provide an evidence base for the prevalence and distribution of dissociation in adults suffering from mental disorders.
METHOD
Study Selection We searched the following databases for primary stud- ies through November 2016: PubMed, PsycINFO, Web of Science, and Academic Search Premier. Our search strategy aimed at articles using the DES or the German version of the scale (FDS) (49, 50) in adults with mental disorders. Although there are formal differences between versions I and II of the DES (visual analogue scale versus Likert-type scale, both ranging from 0 to 100), differences in the results for the two versions have been shown to be negligible (51). Therefore, we decided not to differentiate between the versions of the scale. We developed the search strategy for PsycINFO (“dissoc* exper* scale” OR “FDS”) and adapted it for the other databases. We reviewed relevant review articles and related systematic reviews to identify
studies that were missed in the database searches. If full text was not retrievable from online databases or university li- braries, we contacted the corresponding authors. There were no language or publication date restrictions.
Two trained investigators independently screened titles and abstracts for relevance. In the full-text screening, the following inclusion criteria were imposed: 1) studying a population with mental disorders diagnosed according to ICD (52) or DSM; 2) reporting the sample size and the mean score and standard deviation on the DES, or sufficient in- formation to calculate them; and 3) specification of psy- chometric properties fortranslationsofnon-English versions of the DES. Data were extracted by two independent raters using a standard form and systematically screened for full agreement between raters. Every disagreement was resolved by discussion within the review team. The protocol for this meta-analysis is available in PROSPERO (the “International prospective register of systematic reviews”) and can be accessed at http://www.crd.york.ac.uk/prospero/display_ record.asp?ID=CRD42015020731.
Data Synthesis Diagnostic group, mean and standard deviation of the dis- sociation score, and number of participants were extracted from the primary studies. For each diagnostic group, the random-effects model described in DerSimonian and Laird (53) was used to calculate a group-specific mean and the 95% confidence interval. This approach allows for the integration of data from intrinsically heterogeneous populations that result, for example, from the use of different diagnostic systems. To quantify heterogeneity of the dissociation scores
TABLE 1. Overview of the Results of a Meta-Analysis of Dissociation in Psychiatric Disordersa
Diagnostic Group k N Mean
DES Score 95% CI I2 (%)
Dissociative identity disorder 29 1,313 48.7 46.4, 50.9 77.9 Dissociative disordersb 70 3,073 38.9 36.1, 41.6 95.3 Posttraumatic stress disorder 33 2,106 28.6 25.6, 31.5 96.9 Borderline personality disorder 27 1,705 27.9 25.3, 30.6 89.2 Conversion disorder 20 857 25.6 21.5, 29.7 93.4 Depersonalization/derealizationdisorder 16 759 25.1 22.7, 27.4 80.2 Anorexia nervosa 6 253 24.1 16.3, 31.9 92.9 Bulimia nervosa 8 353 22.0 16.9, 27.0 90.5 Gambling disorder 4 187 19.9 7.9, 31.8 98.5 Alcohol use disorder 12 1,467 19.7 16.5, 23.0 97.5 Somatic symptom disorder 4 132 18.8 16.4, 21.2 16.1 Feeding and eating disordersb 24 1,401 18.6 16.0, 21.2 91.6 Schizophrenia 17 594 17.8 15.6, 20.2 80.5 Other substance-related disorders 14 1,107 17.7 14.7, 20.7 91.9 Panic disorder 11 319 15.6 10.8, 20.4 94.9 Obsessive-compulsive disorder 14 858 15.3 13.2, 17.4 80.3 Depressive disordersb 12 833 15.3 11.2, 19.4 98.1 Anxiety disordersb 19 615 15.2 12.4, 18.0 93.1 Bipolar and related disordersb 7 208 14.8 8.8, 20.8 97.3 Total 216 15,219
a Articles that reported on more than one diagnostic group were included in every category the authors reported dissociation scores on. Diagnostic groups are sorted in descending order of Dissociative Experiences Scale (DES) mean score. k=number of included studies; N=number of patients included in diagnostic group; I2= heterogeneity statistic.
b DSM-5 main category.
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LYSSENKO ET AL.
between studies, we used I2 (54)—an index, based on chi- square statistics and degrees of freedom, that was recom- mended for Cochrane Reviews (55). Because only descriptive data on dissociation scores were included in the analysis, the risk of bias in the primary studies was assumed to be unlikely and therefore was not assessed. Data synthesis was conducted with R, version 3.2.4 (56), using the metafor package (57).
RESULTS
The search in the electronic databases yielded 1,907 different articles (Figure 1). After exclusion of 660 articles during title or abstract screening, 1,247 articles were retrieved for full- text screening, of which 1,026 were subsequently excluded; reasons for exclusion are listed in Figure 1. Across all di- agnostic groups, weincluded 216 articles with a total of 15,219 individuals.
To calculate meta-analytic statistics, the original studies were grouped according to the DSM diagnosis described in the articles. For some diagnoses, this procedure revealed specific subcategories of DSM chapters (e.g., gambling dis- orders). For some categories, only articles reporting on broader categories or entire DSM chapters (e.g., bipolar disorders) werefound. To avoid the confounding influence of diagnostic specification, we included articles reporting on subcategories in both the relevant subcategory as well as the corresponding broader category. Articles that reported on more than one diagnostic group were included in every category the authors reported dissociation scores on. In cases ofco-occurringdisorders,weincludedtheindividualsinboth categories. We included all subcategories in which at least four studies reported data, regardless of whether this sub- category of disorders is still included in DSM-5. In the final
step, we excluded five studies because there were not enough studies for each diagnosis: one study each on kleptomania (58) and pathological Internet use (59) and three studies on mixed personality disorders (60).
Diagnostic categories, number of individual studies, and number of individual patients as well as statistics are listed in Table 1. A graphical illustration of the results is presented in Figure2.Forestplotsofeachdiagnostic categoryareincluded in the datasupplement that accompanies theonline edition of this article.
The highest dissociation scores were found for dissocia- tive identity disorders, with a mean score of 48.7 (95% CI=46.4, 50.9), based on 29 publications with 1,313 patients (Figure 3; the full reference list of included studies can be found in the online data supplement).
Scores for posttraumatic stress disorder were the second highest, with a mean score of 28.6 (95% CI=25.6, 31.5), based on 33 publications with 2,106 patients (Figure 4).
Scores for borderline personality disorder were third largest, with a mean score of 27.9 (95% CI=25.3, 30.6), based on 27 publications and 1,705 individual patients (Figure 5). Scores for other mental disorders were distributed among (in descending order) conversion disorder (mean=25.6), somatic symptoms disorder (mean=18.8), substance-related and ad- dictive disorders (gambling disorder, mean=19.9; alcohol use disorder, mean=19.7; other substance-related disorders, mean=17.7), feeding and eating disorders (mean=18.6), schizophrenia (mean=17.8), OCD (mean=15.3), depressive disorders (mean=15.3), anxiety disorders (mean=15.2), and bipolar and related disorders (mean=14.8).
Only three categories yielded enough studies to analyze dissociation subfactors: borderline personality disorder, dissociative disorders, and schizophrenia. Patients suffering from borderline personality disorder and schizophrenia
FIGURE 2. Mean Dissociative Experiences Scale Score for Each Diagnostic Group in a Meta-Analysis of Dissociation in Psychiatric Disordersa
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a Error bars indicate 95% confidence interval.
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DISSOCIATION IN PSYCHIATRIC DISORDERS
had the highest scores for absorption, and patients with dis- sociativedisordershadthehighestscoresfordepersonalization/ derealization (see Table S1 in the online data supplement for details).
Heterogeneity, as assessed by I2, was .70% in all anal- yses, except for somatic symptom disorders (I2=16.1%); the highest heterogeneity was observed in gambling disorders (I2=98.5%) (see Table 1).
DISCUSSION
This is the second meta-analysis of dissociation scores in a broad variety of psychiatric disorders. While the first meta- analysis was published more than 20 years ago (43) and comprised85individualstudies,ourmeta-analysis reportson 216 individual studies with more than 15,000 individuals with mental disorders. The largest dissociation scores were found for dissociative disorders, followed by PTSD, borderline personality disorder, and conversion disorder, and the lower range of scores included substance-related and addictive disorders, feeding and eating disorders, schizophrenia, anxiety disorder, OCD, and affective disorders.
Our data confirm some but not all of the results reported in the earlier meta-analysis. Confirming results were found regarding dissociative disorders showing the highest overall
dissociation scores. In their analysis, van Ijzendoorn and Schüngel (43) reported mean dissociation scores of 45.6 for multiple personality disorder (now called dissociative identity disorder), 41.1 for unspecified dissociative disorders, and 35.3 for the category of dissociative disorder not other- wise specified. In our study we differentiated between dis- sociative identity disorder and depersonalization/derealization disorder, as listed in DSM-5 (1). Although the existence of dissociativeidentitydisorderhasbeendiscussedcontroversially (e.g., 61), our result of a mean dissociation score of 48.7 in a total of 1,313 individuals with this diagnosis indicates very high levels of dissociative experience in this diagnostic group. Interestingly, depersonalization/derealization disorder yielded numerically lower DES scores than PTSD and border- line personality disorder. This may be due to the fact that depersonalization/derealization disorder does not cover the entire spectrum of dissociative symptoms, therefore leading to lower overall dissociation scores.
Dissociation scores in PTSD and schizophrenia in our analysis were close to those reported by van Ijzendoorn and Schüngel (43), although their study included only one study onschizophrenia(comparedwith17here)andfourstudieson PTSD (compared with 33 here). Scores in PTSD were the second highest in our analysis, reflecting the importance of dissociation in relation to PTSD (62), for which a dissociative
FIGURE 3. Forest Plot of Dissociative Experiences Scale Scores in Dissociative Identity Disordera
0.00 20.00 40.00 60.00 80.00
Mean
First Author and Year
Berger 1994 (13)
Boon 1993 (18)
Carlson 1993 (28)
Choe 1995 (34)
Dell 2002 (40)
Dorahy 2005 (45)
Draijer 1993 (46)
Ellason 2003 (49)
Frischholz 1990 (70)
Gleaves 1995a (75)
Latz 1995 (99)
Lauer 1993 (100)
Martínez−Taboas 1995 (109)
Nijenhuis 1997 (127)
Nijenhuis 1999 (128)
Pokrajac 1994 (140)
Putnam 1996 (148)
Rodewald 2006 (153)
Ross 1988 (158)
Ross 1989 (157)
Ross 1995 (156)
Sar 1996 (166)
Sar 2007b (165)
Scroppo 1998 (173)
Shearer 1994 (177)
Tutkun 1995 (202)
Wassink 1996 (207)
Welburn 2003 (209)
Yargic 1998 (211)
Random-effects model
DES Score (95% CI)
26.80 (13.80, 39.80)
49.40 (45.49, 53.31)
42.80 (40.31, 45.29)
59.54 (54.09, 64.99)
46.15 (39.01, 53.29)
55.10 (44.29, 65.91)
56.80 (50.93, 62.67)
47.80 (41.87, 53.73)
55.00 (48.45, 61.55)
59.85 (51.83, 67.87)
59.50 (51.12, 67.88)
46.60 (36.59, 56.61)
60.30 (53.64, 66.96)
38.60 (32.27, 44.93)
54.20 (48.02, 60.38)
54.21 (44.00, 64.42)
44.60 (42.04, 47.16)
45.37 (41.73, 49.01)
37.20 (27.07, 47.33)
38.30 (29.14, 47.46)
44.60 (42.33, 46.87)
49.10 (43.40, 54.80)
51.10 (44.39, 57.81)
45.97 (38.16, 53.78)
48.50 (34.23, 62.77)
47.20 (39.29, 55.11)
48.86 (41.92, 55.80)
44.52 (36.23, 52.81)
46.10 (38.26, 53.94)
48.66 (46.38, 50.93)
a Reference numbers refer to the list of analyzed studies included in the online data supplement. DES=Dissociative Experiences Scale.
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LYSSENKO ET AL.
subtype was introduced in DSM-5. Although dissociative symptoms are less pronounced in schizophrenia (mean score, 17.8), they have been studied intensively in this disorder because of similarities in the description of dissociative phe- nomena and psychotic symptoms (63). Empirical studies have yielded varying correlations between schizophrenia and different aspects of dissociation, with depersonalization/ derealization showing the strongest relation (5). Several authors have emphasized the relevance of depersonalization as a mediator between childhood trauma and hallucinatory experiences, thus acting as a risk factor for schizophrenia (e.g., 64). It is hypothesized that depersonalization may facilitate a person’s attribution of their own thoughts to external sources (65), and a trauma-dissociation subgroup within schizophrenia has been proposed (66).
Our data differ from the earlier meta-analysis (43) with respect to eating disorders, anxiety disorders, and affective disorders. While eating disorders and anxiety disorders show considerably higher mean dissociation scores in our analysis than in the earlier one (18.6 compared with 14.5 for eating disorders; 15.2 compared with 10.2 for anxiety disorders), we
found lower scores for affective disorders (15.3 for depressive disorders and 14.8 for bipolar disorders compared with 19.4 for affective disorders in the earlier analysis). Recent re- search points to differential relations between dissociation and symptoms of these disorders. In anorexia nervosa, where thehighestmeandissociationscoreswerefound(meanscore, 24.1), symptoms of depersonalization in the form of body schema distortions have been investigated (67). In bulimia nervosa, dissociative qualities of amnesia, timelessness, and involuntariness seem to play a role in bingeing behavior and severity (6, 68). In anxiety disorders, experiences of depersonalization/derealization have often been described in relationship with panic attacks, although the sequence of incidence is not clear: dissociation might trigger panic attacks—for example, via the fear of losing control—but concomitantsymptomsofpanicattacks,suchashyperarousal or hyperarousal, might also produce dissociation (29). In depressive disorders, the research on mechanisms of disso- ciation is impeded by a strong overlap between depressive symptoms such as emotional numbing, feelings of de- tachment, and restricted emotional responsiveness (69), as
FIGURE 4. Forest Plot of Dissociative Experiences Scale Scores in Posttraumatic Stress Disordera
0.00 20.00 40.00 60.00 80.00
Mean
First Author and Year
Abramowitz 2010 (1)
Akyüz 2007 (4)
Amdur 1996 (6)
Aydin 2012 (8)
Bokhan 2012 (16)
Bolu 2014 (17)
Branscomb 1991 (22)
Bremner 1992 (23)
Callegari 2007 (26)
Chard 2005 (33)
Crowson 1998 (37)
Dasse 2015 (39)
El-Hage 2003 (48)
Espirito-Santo 2008 (51)
Evren 2011 (60)
Favaro 2000 (64)
Favaro 2006 (65)
Frewen 2014 (69)
Frueh 1994 (71)
Geraerts 2007 (73)
Karatzias 2010 (92)
Landre 2012 (96)
Matlack 2010 (110)
Mickleborough 2011 (118)
Najavits 2012 (124)
Nardo 2013 (125)
Nejad 2007 (126)
Öezdemir 2015 (132)
Prasko 2016a (141)
Putnam 1996 (148)
Tapia 2007 (199)
Tapia 2012 (198)
Zucker 2006 (214)
Random-effects model
DES Score (95% CI)
47.30 (40.80, 53.80)
18.70 (14.37, 23.03)
30.43 (27.33, 33.53)
27.93 (17.71, 38.15)
19.20 (18.67, 19.73)
50.24 (43.80, 56.68)
41.11 (36.07, 46.15)
27.00 (22.15, 31.85)
28.75 (23.36, 34.14)
19.48 (15.54, 23.42)
54.16 (48.94, 59.38)
29.80 (23.57, 36.03)
23.03 (19.41, 26.65)
35.00 (31.26, 38.74)
26.34 (22.30, 30.38)
19.10 (11.18, 27.02)
20.00 (13.42, 26.58)
33.17 (30.27, 36.07)
40.10 (33.45, 46.75)
34.50 (30.62, 38.38)
29.80 (26.33, 33.27)
26.80 (20.67, 32.93)
23.87 (21.16, 26.58)
9.30 (5.50, 13.10)
19.44 (15.14, 23.74)
14.60 (10.20, 19.00)
26.01 (23.89, 28.13)
44.40 (40.14, 48.66)
21.56 (15.45, 27.67)
31.50 (28.17, 34.83)
36.87 (28.81, 44.93)
22.80 (14.55, 31.05)
15.10 (13.86, 16.34)
28.57 (25.61, 31.54)
a Reference numbers refer to the list of analyzed studies included in the online data supplement. DES=Dissociative Experiences Scale.
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well as by shared covariates, such as sleep quality and dis- tortions in autobiographic memory (23, 70).
Our analysis is the first to report systematically retrieved mean dissociation scores for borderline personality disorder, somatic symptom disorder, conversion disorder, substance- related and addictive disorders, and OCD. Borderline per- sonality disorder showed dissociation scores similar to those of PTSD in 27 studies (mean score, 27.9). Furthermore, our study confirmed the significance of dissociative symptoms in borderline personality disorder, which has been acknowl- edged by adding dissociative experiences as part of one of the nine criteria for borderline personality disorder in DSM-IV (71). Although classified as a personality disorder, borderline personality disorder is closely associated with traumatic stress. Rates of adverse childhood experiences have been consistently demonstrated to be higher than 50% (72). In- dependent of trauma experience and comorbid diagnoses, almost all patients with borderline personality disorder re- port identity confusion, unexplained mood changes, and depersonalization (73).
“Somatic symptom and related disorders” is a new cate- gory in DSM-5 (1) and comprises a broad spectrum of disorders, including somatic symptom disorder (formerly known as somatoform disorders), illness anxiety disorders, conversion disorder (functional neurological symptom dis- order), and factitious disorder. Notably, conversion disorder
is part of the dissociative spectrum in ICD-10 (52), and dissociation scores were in a range similar to those of other dissociative and trauma-related disorders in our meta- analysis.
The high mean dissociation scores for addictive disorders— 19.9 for gambling disorder, 19.7 for alcohol use disorder, and 17.7 for other substance-related disorders—may be partly related to comorbidities with PTSD, borderline personal- ity disorder, and dissociative disorders (74–76). General findings regarding the link between dissociation and sub- stance abuse have been inconsistent but suggest lower scores in samples without comorbid disorders (77–79). The mean dissociation score of 15.3 for OCD falls within the lower range of dissociative symptoms. Nevertheless, dis- sociation has gained increasing attention in this area of research. On a symptomatic level, dissociative amnesia has been related to checking compulsion (80). This effect does not seem to be linked to poorer memory or reality moni- toring performance but rather to a reduced confidence in these abilities (81).
Recent population-based studies show mean dissociation scores in the general population of 8 in a Finnish sample (N=2,001)(82)and10inaPortuguesesample(N=224)(83).In their meta-analysis, van Ijzendoorn and Schüngel (43) report a mean score of 11.6 for healthy subjects. Those numbers appear to be considerably lower than all mean dissociation
FIGURE 5. Forest Plot of Dissociative Experiences Scale Scores in Borderline Personality Disordera
0.00 20.00 40.00 60.00 80.00
Mean
First Author and Year
Barnow 2011 (10)
Berger 1994 (13)
Brodsky 1995 (24)
Frewen 2014 (69)
Grambal 2016 (77)
Kanter 2001 (91)
Kleindienst 2011 (93)
Korzekwa 2009 (94)
Krause-Utz 2014 (95)
Lauer 1993 (100)
Löffler-Stastka 2009 (106)
Macchi 1998 (107)
Mazzotti 2016 (111)
Pokrajac 1994 (140)
Putnam 1996 (148)
Ross 2007 (155)
Russ 1996 (160)
Sar 2003 (163)
Semiz 2005 (176)
Semiz 2008 (175)
Shearer 1994 (177)
Simeon 2003c (187)
Turner 1998 (201)
Vuchelen 1996 (203)
Zanarini 2000 (213)
Zweig-Frank 1994a (215)
Zweig-Frank 1994b (216)
Random-effects model
DES Score (95% CI)
21.04 (16.49, 25.59)
24.40 (13.37, 35.43)
19.58 (15.44, 23.72)
30.22 (28.29, 32.15)
19.06 (15.95, 22.17)
40.17 (32.45, 47.89)
25.80 (21.46, 30.14)
26.90 (18.39, 35.41)
32.25 (25.33, 39.17)
17.70 (9.65, 25.75)
19.10 (14.48, 23.72)
30.59 (25.15, 36.03)
29.60 (26.61, 32.59)
39.31 (32.11, 46.51)
21.60 (14.85, 28.35)
22.70 (19.06, 26.34)
32.87 (25.87, 39.87)
44.41 (35.56, 53.26)
41.96 (35.59, 48.33)
41.33 (37.77, 44.89)
25.02 (19.75, 30.29)
25.80 (18.63, 32.97)
30.85 (25.05, 36.65)
30.65 (24.61, 36.69)
21.80 (19.66, 23.94)
22.36 (18.07, 26.65)
24.80 (21.43, 28.17)
27.95 (25.32, 30.57)
a Reference numbers refer to the list of analyzed studies included in the online data supplement. DES=Dissociative Experiences Scale.
Am J Psychiatry 175:1, January 2018 ajp.psychiatryonline.org 43
LYSSENKO ET AL.
scores calculated for mental disorders in our analysis. Van Ijzendoorn and Schüngel’s conclusion that “the means for normals and nondissociative patients were remarkably similar” (43, p. 372) does not seem to be supported by our results. The variety of mental disorders ranging between 15 and 25 in dissociation scores clearly speaks for dissociative experience as an unspecific and ubiquitous psychopatho- logical phenomenon. From a clinical perspective, this finding underlines the importance of careful evaluation of disso- ciativesymptoms,andnotonlyinpatientswithdissociativeor trauma-related disorders.
Our study has several limitations. Although the overall number of included studies was quite large, the number of studies and subjects per diagnostic category varied sub- stantially. We only included categories with at least four individual studies, but categories varied between four and 66 studies andbetween187and 2,860 subjects. Aswehad no a priori hypothesis to explain heterogeneity, we did not carry out subgroup analysis. Heterogeneity may be rooted in dif- ferent factors, including heterogeneity of the diagnostic entity, diagnostic shifts over time, and differences between individual studies, for example, with respect to diagnostic procedures, gender distribution, and the countries of origin. Most likely, comorbidity and trauma experiences also in- fluence dissociation scores and should be systematically considered in future studies. Finally, we note that the DES is a self-rating instrument and that certain dissociative fea- tures may be over- or underrepresented in comparison to observer-based ratings (84).
In summary, our meta-analysis confirms the prevalence of dissociative symptoms not only in dissociative disorders, posttraumatic stress disorder, and borderline personality disorder, but in nearly all mental disorders. Research on the distinct diagnostic categories suggests a variety of mecha- nisms linking dissociative experiences to a higher burden of illness and detrimental effects on treatment. An evaluation of dissociation should therefore be part of every careful psychopathological assessment, and future studies should engage a transdiagnostic perspective to enhance the devel- opment of treatment modules to deal with dissociative symptoms.
AUTHOR AND ARTICLE INFORMATION
From the Institute for Psychiatric and Psychosomatic Psychotherapy, Central Institute of Mental Health, Mannheim, Germany; the Depart- ment of Psychosomatic Medicine and Psychotherapy, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; the Depart- ment of Psychiatry, Schulich School of Medicine and Dentistry, Western University, London, Ontario; and the Department of Health, Antwerp University, Antwerp, Belgium.
The first two authors contributed equally.
Address correspondence to Ms. Lyssenko ([email protected]).
Dr. Schmahl has received advisory panel payments from Boehringer Ingelheim. The other authors report no financial relationships with commercial interests.
Received Jan. 6, 2017; revisions received April 22, June 1, and June 19, 2017; accepted June 26, 2017; published online September 26, 2017.
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