Running head: EFFECTS OF DISSOCIATION
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Effects of Dissociation on Treatment Outcome: A Systematic Literature Review
Katherine L. Hilton
Mississippi College
Author Note
Katherine L. Hilton, Department of Psychology and Counseling, Mississippi College.
Correspondence concerning this article should be addressed to Katherine L. Hilton, 2906
North State St. Suite #204, Jackson, MS 39216. Email: katherinelhilton@gmail.com
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Abstract
Dissociation is an often ignored or misunderstood phenomenon that has been found to negatively
impact treatment of many co-occurring disorders. A review of current literature would motivate
clinicians to recognize and address dissociation to improve treatment outcome.
Keywords: dissociation, treatment outcome, literature review
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Effects of Dissociation on Treatment Outcome: A Literature Review
According to the National Institute for Mental Health over 36.2 million Americans
received mental health services in just one calendar year (NIMH; 2014a), spending $57.5 billion
dollars nationwide (NIMH, 2014b). Those who received treatment represented only half of the
total population of Americans that met diagnostic criteria for a psychiatric disorder in that same
year (NIMH, 2014b). The need for services is great, and the number of people seeking mental
health treatment in the United States is growing (NIMH, 2014c). To meet these mental health
care needs, it is imperative that treatment becomes increasingly effective.
Effective treatments are defined by having both efficacy and effectiveness (Gertlehner,
Hasenc, & Nissman, 2006). Efficacy is the ability to achieve desired treatment results in
controlled research trials in which there is a clearly defined treatment, population, and set of
outcome goals (Chambless, 1998). Efficacy is best supported by randomized clinical trials that
have been replicated and still achieve desired treatment outcomes (Chambless, 1998). Once a
treatment’s efficacy has been proven under ideal conditions, effectiveness is measured in clinical
settings under average conditions (Gertlehner et al., 2006). When efficacy and effectiveness are
established, the practice is referred to as an evidence-based practice (EBP). EBPs are applied to
clinical practice to achieve positive treatment outcomes.
The first step in applying EBP is to understand the client and his or her diagnostic
presentation (Byng, 2012; Caldwell, Bennett, & Mellis, 2012; Rice, 2013). While assessment is a
common practice, the process can be difficult for complex clinical presentations (Rice, 2013;
Rishel, 2007). This is especially true when clients present with interwoven diagnoses that relate
to the experience of trauma (Ellason, Ross, & Fuchs, 1996, International Society for the Study of
Trauma and Dissociation [ISSTD], 2011; Lamagna & Gleiser, 2007; Sprang, Craig, & Clarck,
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2007). One aspect of trauma related symptomology that is not often addressed in screening and
assessment is dissociation (ISSTD, 2011).
Dissociation
Dissociation is defined as a disruption in typically integrated mental functioning of
experience, especially in regard to “consciousness, memory, identity, or perception” (APA,
2000, p. 519). There are four main types of dissociation: depersonalization, derealization,
dissociative amnesia, and dissociative identity disruption. The majority of people experience
dissociation at least once in their lifetime (American Psychological Association [APA], 2013;
Ross, Joshi, & Currie, 1990). The most common form can be described as “highway hypnosis”
or “spacing out” in which a person loses awareness of the passage of time or changes in his or
her surroundings (Dell, 2009). Typically these instances of dissociation are brief and easily
forgotten. Other common instances of dissociation are more memorable, especially when they
relate to experiences of trauma.
Peritraumatic Dissociation
Peritraumatic dissociation refers to the use of dissociation when in a life-threatening
situation (Marmar et al., 1994). Peritraumatic dissociation is characterized by its spontaneous
and survival-related nature (Dell, 2009), and is considered a normal and adaptive response to
trauma (Barlow & Freyd, 2009; Bonanno, Keltner, Holen, & Horowitz, 1995; Dell, 2009; Freyd,
1994; Marmar et al., 1994; Schauer & Elbert, 2010). Adaptive responses to trauma are
exemplified in common reactions to motor vehicle accidents. Many people describe a sensation
of time moving slowly. Others may feel as though they were watching a movie rather than
experiencing the accident themselves. Some stay fully aware of their experience and
surroundings, but later are unable to recall the events leading up to the accident. These different
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responses are examples of dissociation used to cope with the overwhelming experience of a lifethreat.
Peritraumatic dissociation has many benefits including: (a) acute attention on the source
of danger (Bryant, 2009), (b) reduction of awareness of physical and emotional pain (Bonanno et
al., 1995; Freyd, 1994; Schauer & Elbert, 2010), and (c) an increased chance for survival (Lang,
Davis, & Ohman, 2000). However, dissociation that is adaptive during trauma is not always
beneficial afterward. When an individual relies too heavily on dissociative coping, maladaptive
dissociation can arise.
Maladaptive Dissociation
Dissociation can be experienced separately from adaptive functioning. Maladaptive
dissociation can occur as a single symptom or in one of three domains: (a) a dissociative
disorder, (b) a characteristic of trauma related disorders, or (c) a symptom that is co-occurring
with another disorder.
Dissociative disorders. There are three types of dissociative disorders:
depersonalization/derealization disorder, dissociative amnesia, and dissociative identity disorder
(DID). These disorders are all characterized by a disruption of experience. Dissociative amnesia
is a disruption of memory such that a person is unable to recall important autobiographical
information. In a given year, 1.8% of Americans meet diagnostic criteria for dissociative amnesia
(APA, 2013). Depersonalization/derealization disorder is characterized by a recurrent distorted
experience of self or the environment. Although about half of Americans experience an episode
of depersonalization or derealization in their lifetimes, only 2% will meet diagnostic criteria for
this disorder (APA, 2013). DID is characterized by an interruption in the experience of identity
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and affects 1.5% of the general US population (APA, 2013). These disorders are not the only
appearance of dissociation within the DSM-5.
Other disorders with dissociative criteria. Two other DSM-5 disorders include
dissociation in diagnostic criteria: PTSD and borderline personality disorder (APA, 2013). One
of the defining features of PTSD is the experience of flashbacks of the traumatic event(s).
Flashbacks are inherently dissociative and are deemed “dissociative reactions” (APA, 2013, p.
271) in the DSM-5. Dissociative amnesia is also listed as a potential cognitive element of this
disorder. Because dissociation can heavily impact the experience of PTSD, the DSM-5 includes
the specifier “with dissociative symptoms” (APA, 2013, p. 272). This specifier indicates a client
is recurrently experiencing either depersonalization or derealization.
Although the borderline personality disorder diagnosis does not have a dissociative
specifier, it does include two criteria that deal with dissociation. The first of these criteria is
“severe dissociative symptoms” (APA, 2013, p. 663). The second dissociative criterion is
“identity disturbance: markedly and persistently unstable self-image or sense of self” (APA,
2013, p. 663). Since two of the nine criteria relate to dissociation, it reasonable to assume that
dissociation can be a significant aspect of borderline symptomology. Research suggests that
dissociation can also be significant when the criteria for a disorder do not include dissociation.
Dissociation co-occurring with other disorders. Dissociation has been found to be a
co-occurring issue for clients diagnosed with a wide array of other mental health disorders.
Clients with somatization disorder (now somatic symptom disorder [APA 2013]), experience
high rates of dissociation when compared to non-clinical populations (Brown, Schrag, &
Trimble, 2005). This is also true for childhood sexual abuse survivors who experience somatized
anxiety (Maynes & Feinauer, 1997).Persons with obsessive-compulsive disorder (OCD) also
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experience high levels of dissociation, especially those who engage in compulsive checking
behavior (Hollander & Benzaquen, 1997). Fontonelle and colleagues’ (2007) study demonstrated
comparable levels of dissociation in clients with OCD and social anxiety disorder. Similar rates
of dissociation have also been found among clients with PTSD and clients with panic disorder
with agoraphobia (Pfaltz, Michael, Meyer, & Wilhelm, 2013). Other disorders that often cooccur with dissociation include depression (Hagenaars, van Minnen, & Hoogduin, 2010),
bulimia nervosa and binge eating (Hallings-Pott, Waller, Watson, & Scragg, 2005), and
schizophrenia (Braehler et al., 2013).
Potential Effect of Dissociation on Treatment Outcome
Dissociation can “pose a serious obstacle to successful treatment” (Schauer & Elbert,
2010, p. 109). Because dissociation is a disruption of normal functioning, dissociating during
treatment can impede progress (Schauer & Elbert, 2010). In a 1998 study by Michelson, June,
Vives, Testa, and Marchione (1998) dissociation was found to interrupt treatment for anxiety
disorders, even when clients did not meet criteria for a dissociative disorder. A later study by
Rufer and colleagues (2006) found that OCD clients with higher levels of dissociation
experienced earlier termination, a greater lack of treatment response, and more severe OCD
symptoms post-treatment. In a study of short term inpatient mental health clients, Spitzer et al.
(2007) found a positive correlation between higher levels of dissociation and poorer treatment
outcomes for clients with a wide array of non-psychotic disorders. This negative impact has also
been shown in treatments for borderline personality disorder (Kleindienst et al., 2011) and some
treatments for PTSD (Hagenaars et al., 2010). It is important that the clinical community
understand the effects of dissociation on treatment so that these treatment failures can be
prevented.
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Statement of the Problem
The problem of this literature review is the effects of dissociation on treatment outcome.
An additional concern is to identify specific treatments and disorders that are the most impacted
by dissociation.
Significance of the Study
This study could be useful in identifying an underrepresented variable that has an impact
on treatment outcome. Results could encourage clinicians to screen for and address dissociation
before or during treatment to increase treatment effectiveness. This study could also encourage
clinicians to consider an overlooked cause of lack of progress or dropout.
Research Questions
1. What effects does dissociation have on treatment outcomes?
2. Does dissociation negatively influence treatments for certain co-occurring disorders?
3. How could screening for dissociation improve treatment of other disorders?
Method
This systematic literature review will be conducted over three databases. Results will be
limited to articles published between 1980 and 2014. Titles and abstracts will be reviewed and
studies where dissociation was adequately assessed and treatment outcome data is presented will
be included. Results will be recorded and reported following the Preferred Reporting Items for
Systematic reviews and Meta-Analyses (PRISMA) statement.
The PRISMA statement is a guide for reporting research results (Liberati et al., 2009;
Moher, Liberati, Tetzlaff, Altman, & The PRISMA Group, 2009). An interdisciplinary team of
29 researchers and clinical professionals created the PRISMA statement, updating the 1999
Quality Of Reporting Of Meta-Analysis statement (QUOROM; Liberati et al., 2009). The
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statement includes a 27-item checklist of aspects of the research that should be reported (see
Appendix A; Moher et al., 2009). These aspects range from clear descriptions of each stage of
research to discussions of many types of bias. Additionally, a flow diagram outlines four stages
of systematic review that should be reported: identification, screening, eligibility, and included
studies (see Appendix B; Moher et al., 2009). An article provides full guidelines and
justifications for the checklist and flow diagram (see Liberati et al., 2009).
Locating Appropriate Articles
The following databases will be searched for studies focused on the effects of
dissociation during treatment: PsychINFO, PsychARTICLES, and SocINDEX. Databases will be
searched using the following terms found in Table 1. Since the PRISMA statement allows for
gathering resources by many means (Liberati et al., 2009), articles will also be located by reading
references of discovered articles. A full explanation of this process will be provided as indicated
by the PRISMA statement.
Inclusion Criteria
To meet inclusion criteria, dissociation in the published reports must be measured by the
use of psychometrically sound assessments. Ideally dissociation would be measured by the
following assessments:

Structured Clinical Interview for DSM–IV Dissociative Disorders–Revised (SCID-D-R;
Steinberg, 1994)

Multidimensional Inventory of Dissociation (MID; Dell, 2006)

Dissociative Experiences Scale (DES; Bernstein & Putnam, 1993)

Dissociative Disorders Interview Schedule (DDIS; Ross et al., 1989)
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Exclusion of other measures could limit the pool of available studies for the literature review.
Therefore, any measure of dissociation that has been previously published and tested for validity
and reliability will be included (i.e., Briere, 1995). This includes studies that utilized subscales or
items from other assessments.
Exclusion Criteria
There are only three exclusion criteria for this study. Studies will be limited to those that
are published in English. Studies in non-peer reviewed journals will be excluded, including
newsletters, announcements, and other media. Finally, studies will be excluded if the focus of
treatment is reducing symptoms of a dissociative disorder.
Definitions of Terms
Dissociation
The DSM-5 (APA, 2013) defines the core feature of dissociative disorders as “a
disruption of and/or discontinuity in the normal integration of consciousness, memory, identity,
emotion, perception, motor control, and behavior” (p. 519). For the purposes of this study,
dissociation will refer to behavior or experiences that are in line with the DSM-5 classifications
of dissociative disorders. However, since dissociation is a normal mental function (Freyd, 1994;
Putnam, 1989; Schaur & Elbert, 2010), studies will still be included even when participants’
levels of dissociation do not meet the DSM-5 criteria for dissociative disorders. The following
experiences of dissociation encompass the definition of dissociation for the current study:

Depersonalization – Depersonalization is the experience “of unreality or detachment
from one’s mind, self, or body” (APA, 2013, p. 291). Depersonalization is not
delusional since there is insight that the experience is subjective (Hunter, Sierra, &
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David, 2004). This type of dissociation is a disruption of perception and may also
affect emotion or consciousness.

Derealization – Similar to depersonalization, derealization is the experience “of
unreality or detachment” (APA, 2013, p. 291), but describes detachment from a
person’s surroundings. Derealization is also and disruption of perception, and is also
not delusional because insight remains intact (Hunter et al., 2004).

Dissociative amnesia – Dissociative amnesia is characterized by a disruption in
memory and potentially identity. The key feature of dissociative amnesia is the
“inability to recall autobiographical information that is inconsistent with normal
forgetting” (APA, 2013, p. 291). There are three types of dissociative amnesia
distinguished by the type and amount of information that is not available: localized
(i.e., time period dependent), selective (i.e., event related), and generalized (i.e., all
autobiographical history; APA, 2013).

DID – DID is the most complex dissociative disorder and is “characterized by a) the
presence of two or more distinct personality states … and b) recurrent episodes of
amnesia” (APA, 2013, p. 291). It represents the most comprehensive disruption and
can affect all domains mentioned in the DSM-5 definition of dissociative disorders.
Treatment
The definition of treatment in this study will refer to any number of interventions in the
counseling and psychotherapy field. Since the goal of this literature review is to collect
information on many forms of treatment, no study will be excluded based on the model or
approach to treatment.
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Treatment Outcome
Treatment outcome refers to changes made and/or maintained throughout treatment that
can be reasonably attributed to the treatment. The most valid means of assessing treatment
outcome are to use multiple methods of assessments including instruments that have been
empirically supported in previous studies (Chambless, 1998). However, treatment outcome can
go beyond measures of symptom reduction to include potential side effects, client and clinician
satisfaction, personality change, adaptive functioning, and quality of life (APA Presidential Task
Force on Evidence-Based Practice, 2006; Rice, 2013). For the purposes of this study, treatment
outcome will be defined broadly to include any observed differences relating to treatment. This
broad definition will allow for a complete picture of the effects of dissociation on treatment.
Organization of Remainder of the Study
Chapter one has presented an introduction to dissociation and its potential effects on
treatment outcome. Chapter one also outlined the statement of the problem, research questions,
significance of the study, and definitions of important terms. Chapter two will contain a review
of related literature on dissociation, including: (a) theories of development, (b) current views on
how dissociation operates in trauma-related diagnoses, and (c) available assessment procedures
and treatments. Chapter three will contain methodology and procedures of the literature review
including an expanded section on search term selection, inclusion and exclusion criteria, and the
decision making process. Chapter four will contain the results of the literature review. Finally,
chapter five will discuss the results and the implications for clinical practice.
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Table 1
Search Terms
Dissociation
Treatment
Co-occurring Disorders
Dissociation
Treatment
Comorbidity
Dissociative
Outcome
Co-occurring Disorders
Dissociate
Efficacy
Post-traumatic Stress Disorder
Depersonalization
Effectiveness
Borderline Personality Disorder
Derealization
Treatment Response
Obsessive-Compulsive Disorder
Identity disruption
Panic Disorder
Binge eating
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Appendix A
The PRISMA Checklist
TITLE
Title - Identify the report as a systematic review, meta-analysis, or both.
ABSTRACT
Structured summary - Provide a structured summary including, as applicable: background;
objectives; data sources; study eligibility criteria, participants, and interventions; study
appraisal and synthesis methods; results; limitations; conclusions and implications of
key findings; systematic review registration number.
INTRODUCTION
Rationale - Describe the rationale for the review in the context of what is already known.
Objectives - Provide an explicit statement of questions being addressed with reference to
participants, interventions, comparisons, outcomes, and study design (PICOS).
METHODS
Protocol and registration - Indicate if a review protocol exists, if and where it can be
accessed (e.g., Web address), and, if available, provide registration information
including registration number.
Eligibility criteria - Specify study characteristics (e.g., PICOS, length of follow-up) and
report characteristics (e.g., years considered, language, publication status) used as
criteria for eligibility, giving rationale.
Information sources - Describe all information sources (e.g., databases with dates of
coverage, contact with study authors to identify additional studies) in the search and
date last searched.
Search - Present full electronic search strategy for at least one database, including any limits
used, such that it could be repeated.
Study selection - State the process for selecting studies (i.e., screening, eligibility, included in
systematic review, and, if applicable, included in the meta-analysis).
Data collection process - Describe method of data extraction from reports (e.g., piloted
forms, independently, in duplicate) and any processes for obtaining and confirming
data from investigators.
Adapted from: Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group (2009). Preferred Reporting Items for Systematic
Reviews and Meta-Analyses: The PRISMA Statement. PLoS Med 6(6): e1000097. doi:10.1371/journal.pmed1000097 “The
PRISMA Statement and the PRISMA Explanation and Elaboration document are distributed under the terms of the Creative
Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the
original author and source are credited”
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METHODS (continued)
Data items - List and define all variables for which data were sought (e.g., PICOS, funding
sources) and any assumptions and simplifications made.
Risk of bias in individual studies - Describe methods used for assessing risk of bias of
individual studies (including specification of whether this was done at the study or
outcome level), and how this information is to be used in any data synthesis.
Summary measures - State the principal summary measures (e.g., risk ratio, difference in
means).
Synthesis of results - Describe the methods of handling data and combining results of
studies, if done, including measures of consistency (e.g., I2) for each meta-analysis.
Risk of bias across studies - Specify any assessment of risk of bias that may affect the
cumulative evidence (e.g., publication bias, selective reporting within studies).
Additional analyses - Describe methods of additional analyses (e.g., sensitivity or subgroup
analyses, meta-regression), if done, indicating which were pre-specified.
RESULTS
Study selection - Give numbers of studies screened, assessed for eligibility, and included in
the review, with reasons for exclusions at each stage, ideally with a flow diagram.
Study characteristics - For each study, present characteristics for which data were extracted
(e.g., study size, PICOS, follow-up period) and provide the citations.
Risk of bias within studies - Present data on risk of bias of each study and, if available, any
outcome-level assessment (see Item 12).
Results of individual studies - For all outcomes considered (benefits or harms), present, for
each study: (a) simple summary data for each intervention group and (b) effect
estimates and confidence intervals, ideally with a forest plot.
Synthesis of results - Present results of each meta-analysis done, including confidence
intervals and measures of consistency.
Risk of bias across studies - Present results of any assessment of risk of bias across studies
(see Item 15).
Additional analysis - Give results of additional analyses, if done (e.g., sensitivity or
subgroup analyses, meta-regression [see Item 16]).
Adapted from: Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group (2009). Preferred Reporting Items for Systematic
Reviews and Meta-Analyses: The PRISMA Statement. PLoS Med 6(6): e1000097. doi:10.1371/journal.pmed1000097 “The
PRISMA Statement and the PRISMA Explanation and Elaboration document are distributed under the terms of the Creative
Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the
original author and source are credited”
EFFECTS OF DISSOCIATION
22
DISCUSSION
Summary of evidence - Summarize the main findings including the strength of evidence for
each main outcome; consider their relevance to key groups (e.g., health care providers,
users, and policy makers).
Limitations - Discuss limitations at study and outcome level (e.g., risk of bias), and at review
level (e.g., incomplete retrieval of identified research, reporting bias).
Conclusions - Provide a general interpretation of the results in the context of other evidence,
and implications for future research.
Funding - Describe sources of funding for the systematic review and other support (e.g.,
supply of data); role of funders for the systematic review.
Adapted from: Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group (2009). Preferred Reporting Items for Systematic
Reviews and Meta-Analyses: The PRISMA Statement. PLoS Med 6(6): e1000097. doi:10.1371/journal.pmed1000097 “The
PRISMA Statement and the PRISMA Explanation and Elaboration document are distributed under the terms of the Creative
Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the
original author and source are credited”
EFFECTS OF DISSOCIATION
23
Appendix B
PRISMA Flow Chart
From: Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group (2009). Preferred Reporting Items for
Systematic Reviews and Meta-Analyses: The PRISMA Statement. PLoS Med 6(6): e1000097.
doi:10.1371/journal.pmed1000097 “The PRISMA Statement and the PRISMA Explanation and Elaboration document
are distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use,
distribution, and reproduction in any medium, provided the original author and source are credited”