Chapter 11 Steven Jay Lynn, Joanna M. Berg, Scott O. Lilienfeld, Harald Merckelbach, Timo Giesbrecht, Michelle Accardi, and Colleen Cleere “The most recent edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5; American Psychiatric Association [APA], 2013) defines dissociative disorders as conditions marked by a disruption of and/or discontinuity in the normal integration of consciousness, memory, identity, emotion, perception, body representation, motor control, and behavior” (p. 291). The presentation of dissociative disorders is often dramatic, perplexing, and highly variable, both within and across individuals. The hallmarks of dissociation are profound and often unpredictable shifts in consciousness, the sense of self, and perceptions of the environment. DSM-5 asserts that the dissociative disorders share a common feature: They are frequently manifested in the wake of trauma and are influenced by their proximity to trauma (p. 291). Later in the chapter, we contrast the posttraumatic theory that is firmly embedded in the DSM-5 account of dissociation with a competing theory that does not conceptualize trauma as a necessary precursor to dissociation. In the course of our discussion, we will present a case study that illustrates the treatment of a patient with dissociative identity disorder (DID) and highlight controversies that have dogged the field of dissociation since the time of Janet’s seminal writings on the topic (1889/1973). The DSM-5 (APA, 2013) identifies three major dissociative disorders that we discuss in turn—dissociative amnesia, depersonalization/derealization, and dissociative identity disorder. We then present an overview of dissociation in general, followed by a more detailed discussion of diagnostic considerations, prevalence, assessment, and etiology specific to each of the dissociative disorders. DSM-5 also includes a fourth category of other specified dissociative disorder, which does not meet full criteria for any dissociative disorder and includes chronic and recurrent syndromes of mixed dissociative symptoms, identity disturbance due to prolonged and intense coercive persuasion, acute dissociative reactions to stressors, and dissociative trance. Additionally, DSM-5 includes a fifth category of unspecified dissociative disorder in which criteria are not met for a specific dissociative disorder and there is insufficient information to make a more specific diagnosis. Finally, DSM-5 currently describes a dissociative subtype of posttraumatic stress disorder in which persistent or recurring feelings of depersonalization and/or derealization are manifested in reaction to trauma-related stimuli. DSM-5 requires that the symptoms of all dissociative disorders must cause significant distress, impairment of functioning in major aspects of daily life, or both, and must not be attributable to the effects of a substance or another medical condition. Some epidemiological studies among psychiatric inpatients and outpatients have reported prevalence rates of dissociative disorders exceeding 10% (Ross, Anderson, Fleischer, & Norton, 1991; Sar, Tutkun, Alyanak, Bakim, & Barai, 2000; Tutkun, Sar, Yargiç, Özpulat, Yank, & Kiziltan, 1998), and a study among community women in Turkey even reported a prevalence rate of 18.3% for lifetime diagnoses of a dissociative disorder (Sar, Akyüz, & Dogan, 2007). In contrast, many authors would take issue with these high prevalence rates in both clinical and nonclinical samples. Indeed, as our discussion will reveal, estimates of the prevalence of dissociative disorders vary widely and are associated with considerable controversy. Although many authors regard symptoms of depersonalization/derealization and dissociative amnesia as core features of dissociation, the concept of dissociation is semantically open and lacks a precise and generally accepted definition (Giesbrecht, Lynn, Lilienfeld, & Merckelbach, 2008). This definitional ambiguity is related, in no small measure, to the substantial diversity of experiences that fall under the rubric of “dissociation.” Dissociative symptoms range in their manifestation from common cognitive failures (e.g., lapses in attention), to nonpathological absorption and daydreaming, to more pathological manifestations of dissociation, as represented by the dissociative disorders (Holmes et al., 2005). This variability raises the possibility that some of these symptoms are milder manifestations of the same etiology or have different etiologies and biological substrates, raising questions about whether dissociation is a unitary conceptual domain (Hacking, 1995; Holmes et al., 2005; Jureidini, 2003). Indeed, van der Hart and his colleagues (van der Hart, Nijenhuis, Steele, & Brown, 2004, 2006) have distinguished ostensibly trauma-related or pathological dissociation, which they term structural dissociation of the personality, from nonpathological dissociative experiences (e.g., altered sense of time, absorption). Structural dissociation, in turn, can be subdivided into levels that encompass primary dissociation, which is thought to involve one purportedly apparently normal part of the personality (ANP) and one emotional part of the personality (EP), secondary structural dissociation, supposedly associated with a single ANP and further division of the EP, and tertiary dissociation, ostensibly limited to DID and characterized by several ANPs and EPs. Nevertheless, as our review will demonstrate, researchers’ attempts to discriminate pathological from nonpathological dissociative experiences psychometrically have been subject to criticism and have been less than uniformly successful (Giesbrecht, Lynn, Lilienfeld, & Merckelbach, 2008; Modestin & Erni, 2004; Waller, Putnam, & Carlson, 1996; Waller & Ross, 1997). Other researchers (Allen, 2001; Cardeña, 1994; Holmes et al., 2005) have proposed two distinct forms of dissociation: detachment and compartmentalization. Detachment consists of depersonalization and derealization, which we describe in some detail later, and related phenomena, like out-of-body experiences. Psychopathological conditions that reflect symptoms of detachment include depersonalization disorder and feelings of detachment that occur during flashbacks in posttraumatic stress disorder (PTSD). Compartmentalization, in contrast, ostensibly encompasses dissociative amnesia, marked by extensive forgetting of autobiographical material, and somatoform dissociation, such as sensory loss and “unexplained” neurological symptoms (Nijenhuis, Spinhoven, Van Dyck, Van der Hart, & Vanderlinden, 1998). The core feature of compartmentalization is a deficit in deliberate control of processes or actions that would normally be amenable to control, as is evident in DID or somatization disorder. Although clinicians may find it helpful to subdivide dissociative symptoms into different symptom clusters (Bernstein-Carlson & Putnam, 1993), attempts to differentiate such clusters on a psychometric basis have not been consistently successful. Dissociation is often presumed to reflect a splitting of consciousness, although it must be distinguished from the superficially similar but much debated concept of Freudian repression. Specifically, dissociation can be described as a “horizontal” split; that is, consciousness is split in two or more parts that operate in parallel. In contrast, repression is more akin to a “vertical” split, in which consciousness is arranged in levels, and traumatic or otherwise undesirable memories are ostensibly pushed downwards and rendered more or less inaccessible. Although the existence of dissociation as a clinical symptom is not much in dispute, dissociative disorders are among the most controversial psychiatric diagnoses. Disagreement generally centers on the etiology of these disorders, with advocates often arguing for largely trauma-based origins (e.g., Dalenberg et al., 2012; Gleaves, 1996). In this light, dissociative symptoms are regarded as manifestations of a coping mechanism that serves to mitigate the impact of highly aversive or traumatic events (Gershuny & Thayer, 1999; Nijenhuis, van der Hart, & Steel, 2010). In contrast, skeptics often emphasize the role of social influences, including cultural expectancies and inadvertent therapist cueing of symptoms (e.g., Lilienfeld et al., 1999; Lynn et al., in press; McHugh, 2008). As we will learn later in the chapter, the controversies stemming from etiology and classification of dissociative disorders extend to their assessment and treatment. We will focus our discussion on chronic dissociative symptoms, rather than dissociation at the time of a highly aversive event (i.e., peritraumatic dissociation). Also, we will not elaborate on the dissociative subtype of PTSD described in DSM-5. However, we will present a number of “state” measures of dissociation because researchers not infrequently consider temporary changes in dissociation in the context of research on more chronic presentations of dissociation. The diagnosis of dissociative amnesia requires that the memory loss is extensive and not attributable to substance use or to a neurological or other medical condition such as age-related cognitive loss, complex partial seizures, or closed-head brain injury and that the symptoms are not better explained by DID, PTSD, acute stress disorder, somatic symptom disorder, or major or mild neurocognitive disorder (APA, 2013, p. 298). This disorder, formerly referred to as psychogenic amnesia, often presents as retrospective amnesia for some period or series of periods in a person’s life, frequently involving a traumatic experience. DSM-5 lists several subtypes of dissociative amnesia. In localized amnesia, the individual cannot recall any information from a specific period of time, such as total forgetting of a holiday week. Selective amnesia involves the loss of memories for some, but not all, events from a specific period of time. In generalized amnesia, individuals cannot recall anything about their entire lives, and in continuous amnesia, individuals forget each new event as it occurs. Finally, systematized amnesia consists of the “loss of memory for specific categories of information” (e.g., sexual abuse, a particular person). These last three types of dissociative amnesia—generalized, continuous, and systematized—are much less common than the others, and may be manifestations of more complex dissociative disorders, such as DID rather than dissociative amnesia alone. Lynn et al. (2014) argued that the central diagnostic criterion for dissociative amnesia is vague and subjective in stipulating that one or more episodes of inability to recall important information must be “…inconsistent with ordinary forgetting” (Dahlenberg et al., p. 522). The reliability of judgments of what constitutes “ordinary forgetfulness” is questionable, and what is “ordinary” hinges on a variety of factors, including the situational context and presence of comorbid conditions. A similar point was raised by Read and Lindsay (2000), who demonstrated that when people are encouraged to remember more about a selected target event, they report their forgetting to be more extensive, compared with individuals who are asked to simply reminisce about a target event. Because rates of reporting vary so widely, it is difficult to obtain reliable epidemiological information regarding dissociative amnesia. Questions concerning the validity of dissociative amnesia as a diagnostic entity are supported by markedly different prevalence rates in the general population across cultures: 0.2% in China, 0.9% and 7.3% in Turkey, and 3.0% in Canada (Dell, 2009). These varying prevalence estimates could reflect genuine cultural differences, but they could just as plausibly reflect different interviewer criteria for evaluating amnesia. The DSM-5 states that dissociative amnesia can present in any age group, although it is more difficult to diagnose in younger children due to their difficulty in answering questions about periods of forgetting and possible confusion with a number of other disorders and conditions, including inattention, anxiety, oppositional behavior, and learning disorders. There may be just one episode of amnesia, or there may be multiple episodes, with each episode lasting anywhere from minutes to decades. Other sources (e.g., Coons, 1998) suggest that most cases occur in individuals in their 30s or 40s, and that 75% of cases last between 24 hours and 5 days. The prevalence of dissociative amnesia is approximately equal between genders. Still others argue that the scientific evidence for the existence of dissociative amnesia is unconvincing, and that barring brain injury or substance abuse or dependence, individuals who have experienced trauma do not forget those events (e.g., McNally, 2003; Pope, Hudson, Bodkin, & Oliva, 1998). Certain cases of purported traumatic amnesia are in fact attributable to organic or other nondissociative causes. For example, when critiquing a “convincing demonstration of dissociative amnesia” (Brown, Scheflin, & Hammond, 1997), McNally (2004) discussed a study (Dollinger, 1985) of two children who witnessed a playmate struck and killed by lightning, and who were later diagnosed with dissociative amnesia. Yet as McNally noted, this diagnosis was clearly mistaken, because the children had also been struck by lightning and knocked unconscious. Amusingly, and perhaps tellingly, Pope, Poliakoff, Parker, Boynes, and Hudson (2007) offered a reward of $1,000 to “the first individual who could find a case of dissociative amnesia for a traumatic event in any fictional or non-fictional work before 1800” (p. 225) on the basis that, whereas the vast majority of psychological symptoms can be found in literature or records dating back centuries, dissociative amnesia appears only in more modern literature beginning in the late 1800s. Over 100 individuals came forward with examples, but none met the diagnostic criteria for the disorder (although the prize later went to someone who discovered a case of dissociative amnesia in a 1786 opera, Nina, by the French composer Nicholas Dalayrac). Although Pope and colleagues’ challenge does not “prove” anything regarding the validity of the disorder, its relative scarcity, and apparently recent (perhaps post late 18th century) development, raise troubling questions about its existence as a natural category or entity. A special form of dissociative amnesia is crime-related amnesia. Many perpetrators of violent crimes claim to experience great difficulty remembering the essential details of the crime they committed (Moskowitz, 2004). Memory loss for crime has been reported in 25%–40% of homicide cases and severe sex offenses. Nevertheless, skeptics believe that genuine dissociative amnesia in these cases is rare. They have pointed out that trauma victims (e.g., concentration camp survivors) almost never report dissociative amnesia (Merckelbach, Dekkers, Wessel, & Roefs, 2003). For example, Rivard, Dietz, Matell, and Widawski (2002) examined a large sample of police officers involved in critical shooting incidents and found no reports of amnesia. Also, recent laboratory research shows that when participants encode information while in a “survival mode,” this manipulation yields superior memory effects (Nairne & Pandeirada, 2008). This finding is difficult to reconcile with the idea of dissociative amnesia while committing a crime. Thus, it is likely that feigning underlies most claims of crime-related amnesia (Van Oorsouw & Merckelbach, 2010). Dissociative fugue (previously called psychogenic fugue) is arguably the most controversial dissociative phenomenon after dissociative identity disorder. In DSM-IV-TR, dissociative fugue (i.e., short-lived reversible amnesia for personal identity, involving unplanned travel or wandering) was listed as a separate diagnosis. In DSM-5, dissociative fugue—defined therein as apparently purposeful travel or bewildered wandering associated with amnesia for identity or other important autobiographical information—is no longer diagnosed as a disorder in its own right, but is instead coded as a condition that can accompany dissociative amnesia. In a fugue (“fugue” has the same etymology as the word “fugitive”) episode, amnesia for identity may be so extreme that a person physically escapes his or her present surroundings and adopts an entirely new identity. If and when this identity develops, it is often characterized by higher levels of extraversion than the individual displayed prefugue, and he or she usually presents as well integrated and nondisordered. Periods of fugue vary considerably across individuals, both in duration and in distance traveled. In some cases, the travel can be a brief and relatively short trip, whereas, in more extreme cases, it can involve traveling thousands of miles and even crossing national borders. While in the dissociative fugue state, individuals often appear to be devoid of psychopathology; if they attract attention at all, it is usually because of amnesia or confusion about personal identity. Again, it is doubtful that fugues constitute a fixed and cross-cultural diagnostic category. Hacking (1995) provides a detailed historical and critical analysis of fugue showing that they first appeared in the 19th century and since that time fluctuated in apparent prevalence and acceptance by the psychiatric community. Although DSM-5 notes that dissociative fugue, with travel, is not uncommon in DID, dissociative fugue may manifest with other symptoms, including depression, anxiety, dysphoria, grief, shame, guilt, stress, and aggressive or suicidal impulses (APA, 2013). Reportedly, the condition often develops as a result of traumatic or stressful events, which has led to controversy and ambiguity regarding the relation between dissociative fugue and PTSD. Precipitants associated with the development of dissociative fugue include war or natural disasters, as well as the avoidance of various stressors, such as marital discord or financial or legal problems (Coons, 1998). Such avoidance suggests that clinicians must be certain to rule out malingering and factitious disorders before diagnosing dissociative fugue. Certain culture-bound syndromes exhibit similar symptoms to dissociative fugue. These include amok, present in Western Pacific cultures (which has given rise to the colloquialism “running amok”); pibloktok, present in native cultures of the Arctic, and Navajo “frenzy” witchcraft, all of which are marked by “a sudden onset of a high level of activity, a trancelike state, potentially dangerous behavior in the form of running or fleeing, and ensuing exhaustion, sleep, and amnesia” for the duration of the episode (APA, 2000, p. 524; Simons & Hughes, 1985). DSM-IV-TR places the population prevalence estimate of dissociative fugue at .02%, with the majority of cases occurring in adults (APA, 2000, p. 524). Ross (2009b) observed that in the approximately 3,000 individuals he treated in his trauma program over a 12-year period, he encountered fewer than 10 individuals with pure dissociative amnesia or pure dissociative fugue, although he noted that symptoms of amnesia and fugue were common in the patients he admitted. Depersonalization/derealization disorder (DDD) is one of the most common dissociative disorders and perhaps the least controversial. In DDD, reality testing remains intact (APA, 2013, p. 302): Individuals are aware that the sensations are not real and that they are not experiencing a break from reality akin to psychosis. In a departure from DSM-IV, in which depersonalization and derealization were diagnosed separately, DSM-5 created a new diagnostic category of depersonalization/derealization disorder. This “lumping” of formerly separate conditions is supported by findings (Simeon, 2009a) that individuals with derealization symptoms do not differ significantly from those with depersonalization accompanied with derealization in salient respects (e.g., illness characteristics, comorbidity, demographics). Greatly contributing to our knowledge about depersonalization symptoms has been the development of well-validated screening instruments, notably the Cambridge Depersonalization Scale (CDS; Sierra & Berrios, 2000; Sierra, Baker, Medford, & David, 2005). Depersonalization episodes are not uncommonly triggered by intense stress and are often associated with high levels of interpersonal impairment (Simeon et al., 1997). Episodes of depersonalization or derealization are also frequently associated with panic attacks, unfamiliar environments, perceived threatening social interactions, the ingestion of hallucinogens, depression, and PTSD (Simeon, Knutelska, Nelson, & Guralnik, 2003). Individuals with DDD are also more likely than healthy individuals to report a history of emotional abuse. In contrast, general dissociation scores are better predicted by a history of combined emotional and sexual abuse (Simeon, Guralnik, Schmeidler, Sirof, & Knutelska, 2001). Nearly 50% of adults have experienced at least one episode of depersonalization in their lifetimes, usually in adolescence, although a single episode is not sufficient to meet criteria for the disorder (Aderibigbe, Bloch, & Walker, 2001). Because depersonalization and derealization are common, DDD should be diagnosed only if these symptoms are persistent or recurrent and are severe enough to cause distress, impairment in functioning, or both. The distress associated with DDD may be extreme, with sufferers reporting they feel robotic, unreal, and “unalive.” They may fear becoming psychotic, losing control, and suffering permanent brain damage (Simeon, 2009a). Individuals with DDD may perceive an alteration in the size or shape of objects around them. Other people may appear mechanical or unfamiliar, and affected individuals may experience a disturbance in their sense of time (Simeon & Abugel, 2006). A diagnosis of DDD requires that the symptoms do not occur exclusively in the course of another mental disorder, nor can they be attributable to substance abuse or dependence or to a general medical condition. Furthermore, DDD should not be diagnosed solely in the context of meditative or trance practices. Symptoms of other disorders, such as anxiety disorders, major/unipolar depression, and hypochondriasis and certain personality disorders, especially avoidant, borderline, and obsessive-compulsive, may also be present (Simeon et al., 1997). Depersonalization and derealization symptoms are often also part of the symptom picture of acute stress disorder (ASD; APA, 2013), which is often a precursor to PTSD. DSM-5 estimates the lifetime prevalence of DDD in the United States as 2%, with a range of 0.8% to 2.8% (see also Ross, 1991), suggesting that DDD might be as common as or more common than schizophrenia and bipolar disorder. DDD is diagnosed almost equally often in women as in men (Simeon et al., 2003). It frequently presents for treatment in adolescence or adulthood, even as late as the 40s, though its onset may be earlier. Estimates of the age of onset of DDD range from 16.1 (Simeon et al., 1997) to 22 years (Baker et al., 2003). The onset and course of DDD vary widely across individuals. Some people experience a sudden onset and others a more gradual onset; some experience a chronic form of the disorder, whereas others experience it episodically. In about two-thirds of people with DDD, the course is chronic, and symptoms of depersonalization are present most of the time, if not continually. Episodes of depersonalization may last from hours to weeks or months, and in more extreme cases, years or decades (Simeon, 2009a). According to DSM-5, “the defining feature of dissociative identity disorder is the presence of two or more distinct personality states or experiences of possession” (APA, 2013, p. 292). Thus, the requirement that people diagnosed with DID must experience distinct identities that recurrently take control over one’s behavior is no longer present. Importantly, in DSM-5 “distinct personality states” replaces the term identities. The diagnostic language in DSM-5 represents a distinct departure from DSM-II (APA, 1968), which used the term multiple personalities, and from DSM-IV (APA, 1994), which labeled the condition dissociative identity disorder to underscore alterations in identity, rather than fixed and/or complete “personalities.” These shifts in diagnostic criteria may prove to be problematic and result in changes in the prevalence rates of DID. For example, what constitutes a personality state or an experience of possession may be open to greater interpretation compared with previous iterations of DSM. Moreover, in DSM-5, signs and symptoms of personality alteration may be not merely “observed by others,” but also “reported by the individual” (APA, 2013; p. 292), further expanding opportunities for the diagnosis of DID. In cases in which alternate personality states are not witnessed, in DSM-5 it is still possible to diagnose the disorder when there are “sudden alterations or discontinuities in sense of self or agency…and recurrent dissociative amnesias” (APA, 2013; p. 293), creating even more latitude and subjectivity in the diagnosis of DID. Moreover, amnesia is no longer restricted to traumatic events and may now be diagnosed in relation to everyday events, which may also increase the base rates of diagnosed DID. Although DSM-5 no longer defines DID in terms of “distinct identities that recurrently take control of the individual’s behavior (DSM-IV, p. 519),” in the remainder of the chapter, we will not refrain from using the terms personalities and identities, insofar as these terms (a) continue to be widely used in the extant literature and (b) encompass “personality states.” To meet diagnostic criteria for DID, an individual’s symptoms cannot be attributable to substance use or to a medical condition, and the “disturbance is not a normal part of a broadly accepted cultural or religious practice” (APA, 2013; p. 292). When the disorder is assessed in children, the symptoms must not be confused with imaginary play. To recognize cultural variants of dissociative phenomena, DSM-5 refers to a “possession form” of DID, which is “typically manifest as behaviors that appear as if a ‘spirit,’ supernatural being, or outside person has taken control, such that the individual begins speaking or acting in a distinctly different manner” (APA, 2013, p. 293). Because such manifestations are not uncommon in different cultures (see Cardeña, van Duijl, Weiner, & Terhune, 2009 for a discussion of trance/possession phenomena), to warrant a diagnosis of DID, the identities must be present recurrently, be unwanted or involuntary, engender significant distress or impairment, and not be a part of accepted cultural/religious practices. In nonpossession forms of DID, there is typically considerable variation in the presentation of symptoms. Nevertheless, the primary identity or personality state in an individual with DID often carries the individual’s given name and tends to be “passive, dependent, guilty, and depressed.” Other personalities, often called “alters,” may be assertive or even aggressive and hostile, and these more dominant identities usually possess more complete memories regarding the individual’s actions and history. Within one individual, there can often be anywhere between 2 and 100 or more personalities, with approximately 50% of individuals reporting 10 or fewer distinct identities, although extreme cases of many as 4,500 alters have been reported (Acocella, 1999). Reported identities are usually just “regular” people, but more extreme and bizarre cases exist. There have been reports of identities claiming to be Mr. Spock from Star Trek, the rock star Madonna, the bride of Satan, and even a lobster. Researchers have documented substantial comorbidity of DID with other disorders. For example, Ellason, Ross, and Fuchs (1996) reported that DID patients met criteria for an average of 8 Axis I disorders and 4.5 Axis II disorders. One-half to two-thirds of patients with DID meet diagnostic criteria for borderline personality disorder (BPD; Coons, Bowman, & Milstein, 1988; Horevitz & Braun, 1984). Conversely, Sar, Akyuz, Kugu, Ozturk, and Ertem-Vehid (2006) found that 72.5% of patients screened for BPD had a dissociative disorder. In one study, researchers (Kemp, Gilbertson, & Torem, 1988) reported no significant differences between BPD and DID patients on measures of personality traits, cognitive and adaptive functioning, and clinician ratings, suggesting noteworthy commonalities between the two conditions. Histories of sexual and physical abuse are also commonly reported in both patient groups, and BPD patients score well above general population norms on measures of dissociation (Lauer, Black, & Keen, 1993). Indeed, Lauer and his colleagues (Lauer, Black, & Keen, 1993) suggested that DID is an epiphenomenon of the combination of BPD with high suggestibility. Individuals with DID often experience additional symptoms, including self-mutilation; suicidal or aggressive behavior; as well as major depression; substance abuse; and sexual, eating, and sleep disorders (Fullerton et al., 2000; North, Ryall, Ricci, & Wetzel, 1993; Ross, 1997). Accordingly, some clinicians have argued that the DID diagnosis really is a severity marker identifying extreme variants of a host of other disorders (for an extensive discussion see North et al., 1993). Many DID patients meet the criteria for schizoaffective disorder (Lauer et al., 1993), and as many as half have received a previous diagnosis of schizophrenia (Ross & Norton, 1988). Indeed, auditory and visual hallucinations are common in both DID and schizophrenia. However, patients with DID commonly report that hallucinated voices originate inside of their heads, whereas patients with schizophrenia tend to perceive the origin of voices outside of their heads and possess less insight into the nature of their symptoms (Coons, 1998; Kluft, 1993). DID patients have been reported to endorse more positive symptoms (e.g., delusions, hallucinations, and suspiciousness) and Schneiderian first-rank symptoms, which include themes of passivity, than schizophrenic patients (Ellason & Ross, 1995; Steinberg, Rounsaville, & Cichetti, 1990). Ellason and Ross (1995) argued that the presence of positive symptoms can be used to formulate an accurate differential diagnosis between the two disorders, although further research regarding this possibility is necessary (for further diagnostic considerations see Steinberg & Siegel, 2008). PTSD is one of the most commonly comorbid conditions with DID (Loewenstein, 1991). Moreover, PTSD patients are more likely to present with symptoms of dissociation (e.g., numbing, amnesia, flashback phenomena) than patients with major depression, schizophrenia, and schizoaffective disorder (Bremner, Steinberg, Southwick, Johnson, & Charney, 1993). DID may be episodic or continuous, and in some cases may remit after the late 40s (APA, 2000). There are documented cases of DID extending decades, and the concept of fragmented or multiple personalities is an ancient one. That said, the number of cases has increased exponentially in the past few decades. Prior to 1970, there were approximately 80 reported cases, but by 1986 that number had ballooned to approximately 6,000. As of 1998, there were approximately 40,000 cases (Lilienfeld & Lynn, in press). Population prevalence estimates vary widely, from extremely rare (e.g., Piper, 1997; Rifkin, Ghisalbert, Dimatou, Jin, & Sethi, 1998) to rates approximating that of schizophrenia (1–2%; Coons, 1998; Ross, 1997). Estimates of DID in inpatient settings range from 1–9.6% (Rifkin et al., 1998; Ross, Duffy, & Ellason, 2002). In addition to the dramatic increase in DID’s prevalence over the past few decades, there has been an increase in the number of “alters” reported, from only two or three separate identities to an average of approximately 16 (interestingly, the exact number reported by Sybil; see below) by 1990. DID is between 3 and 9 times more common in women than men, and women also tend to have more identities (an average of 15, as compared with the male average of 8; APA, 2000). Nevertheless, this imbalanced sex ratio may be an artifact of selection and referral biases (Lynn, Fassler, Knox, & Lilienfeld, 2009). In particular, a larger proportion of males with DID may end up in prisons (or other forensic settings) than in clinical settings (Putnam & Loewenstein, 2000). DID is the most controversial dissociative disorder, and easily among the most controversial disorders in DSM-5. Skeptics of the disorder (Paris, 2012; Piper & Merskey, 2004) argue that its proliferation is in part a function of media exposure. In 1976, the movie Sybil was released, documenting the real-life story of a woman who had supposedly experienced severe child abuse and later developed 16 personalities (but see “Etiological Considerations” section for evidence calling into question significant details of the Sybil case). In addition to the number of cases increasing after the release of this movie, the number of individuals reporting child abuse as a cause of DID also rose drastically (Lilienfeld & Lynn, in press; Spanos, 1996). In contrast, proponents of the disorder respond that clinicians now are simply better equipped to identify the disorder (Gleaves, May, & Cardena, 2001). We elaborate on this etiological debate later in the chapter. A variety of assessment instruments are available to evaluate dissociation and dissociative disorders. In this section, we review commonly used structured interview and self-report measures. The Structured Clinical Interview for DSM-IV (SCID-D; Steinberg, 1985) and its revision (SCID-D-R; Steinberg, 1994) are semistructured interviews that systematically assess five core symptoms of dissociation: amnesia, depersonalization, derealization, identity confusion, and identity alteration. The SCID-D incorporates the DSM-IV criteria for dissociative disorders. The full 250-item administration may take 2–3 hours for psychiatric patients with dissociative symptoms; however, nondissociative psychiatric patients may complete the interview in 30 to 90 minutes, and nonpsychiatric participants in 30 minutes. The severity of each of the five core symptoms is scored in terms of distress, dysfunctionality, frequency, duration, and course. The revised scale was administered in NIMH field trials that encompassed 350 interviews of dissociative and nondissociative adults. Reports from the field trials (N = 141 mixed psychiatric patients) revealed that the interexaminer and temporal reliability of the SCID-D-R ranges from very good to excellent (weighted kappa 0.77–0.86) for both the presence and extent of dissociative symptoms over three time periods. For type of dissociative disorder, interexaminer agreement ranged from 0.72–0.86, and test-retest reliability for the overall presence of a dissociative disorder was good (0.88 over 7-day period). The SCID-D-R possesses good convergent validity, and is capable of distinguishing DID patients from patients with anxiety disorders, substance abuse, personality disorders, eating disorders, and psychotic disorders (Cardena, 2008). The SCID-D may be helpful in discriminating DID from feigning. It also appears to distinguish DID from schizophrenia (Wellburn et al., 2003). Nevertheless, Kihlstrom (2005, p. 3) countered that “even with relatively strict criteria in place, it can be difficult to discriminate between dissociative disorders and bipolar disorder, borderline personality disorder, and even schizophrenia.” The Dissociative Disorders Interview Schedule (DDIS; Ross et al., 1989) is a structured interview used to assist in the diagnosis of dissociative disorders, as well as conditions that often co-occur with it, including somatization disorder, major depressive disorder, and borderline personality disorder. The interview has been used for clinical and research purposes and consists of 16 sections with a total of 131 questions. The interview is highly structured to minimize interviewer confirmation bias and sequenced so that indirect questions about secondary features of DID precede increasingly specific questions. In the original validation study, 80 psychiatric patients from specialized research clinics were interviewed. Patients diagnosed with DID (n = 20) were compared with patients with panic disorder (n = 20), eating disorder (n = 20), and schizophrenia (n = 20). For DID, the DDIS yielded a sensitivity of 90% and a specificity of 100% [see also Ross et al. (1992) who demonstrated high agreement (94.1%) of DDIS classification using the DDIS with independent clinical evaluation]. The authors reported that interrater reliability was adequate (r = .68; Ross et al., 1989). The DDIS has demonstrated good convergent validity, as indexed by high correlations of DID diagnosis scores with the DES (r = .67–.78; Cardena, 2008). Nevertheless, the authors (Ross et al., 1989) cautioned that depersonalization disorder cannot be reliably diagnosed using the DDIS (interrater reliability = .56). The Clinician Administered Dissociation State Scale (CADSS; Bremner et al., 1998) was developed to assess dissociative states. The clinician verbally administers 19 “subject-rated” items on a Likert-type scale ranging from 0 (not at all) to 4 (extremely). Three subscales subsume the subject-rated items: amnesia, depersonalization, and derealization. The clinician also observes the participant’s behavior during the interview and rates eight behaviors presumed to indicate the presence of a dissociative state on the same Likert-type scale as the subject-rated items. In the original study, the CADSS was administered to patients with combat-related PTSD and a comorbid dissociative disorder (PTSD/dissociative) (n = 68). These patients were compared with patients with schizophrenia (n = 22), mood disorders (n = 15), healthy controls (n = 8), and combat veterans without PTSD (n = 11). The CADSS discriminated between patients with PTSD and comorbid dissociative disorders (86% of cases) and patients with the comparison conditions. Furthermore, the CADSS detected changes in dissociative symptoms before and after patients with PTSD participated in a traumatic memories group. These patients showed a significant increase in symptoms compared with baseline, suggesting that the CADSS may be sensitive enough to capture changes in repeated measures designs. Interrater reliability was excellent for the total scale (ICC = .92) and for the subject-rated portion (ICC = .99), but was markedly lower for the observer ratings (ICC = .34). The internal consistency of the CADSS was good to excellent for the total scale (α = .94), subjective portion (α = .94), observer ratings (α = .90), and the individual subscales (α = .74–.90). Recently, Condon and Lynn (in press) reported that the CADSS correlated at r =.63 with the DES-II and reported the internal consistency of the CADSS to be α = .80 in a sample of undergraduates. The Dissociative Experiences Scale (DES; Bernstein & Putnam, 1986) and its revision (DES-II; Bernstein-Carlson & Putnam, 1993) are brief self-report measures of dissociation that can be used in both research and clinical settings to assess individuals within normal and psychiatric populations. Participants rate 28 items pertaining to dissociation in terms of the frequency they are experienced, from 0% to 100%. In the original sample, the test-retest reliability among 192 participants was .84 over a period of 4 to 8 weeks, and split half reliability coefficients ranged from .71 to .96, indicating good internal consistency. In addition, DES scores differentiated participants with a dissociative disorder (e.g., DID) from those without a dissociative disorder (e.g., normal adults, late adolescent college students, alcoholics, phobics). A cutoff of 30 correctly identified 74% of patients with DID and 80% of subjects without DID in a multicenter study (Carlson, Putnam, Ross, Torem, et al., 1991). The DES is the most frequently used self-report measure of dissociation (Brand, Armstrong, & Loewenstein, 2006). Nevertheless, researchers have questioned whether the scale is unidimensional, as would be expected of a factorially pure measure of dissociation. Carlson et al. (1991) reported a three-factor solution—amnesia, absorption (related to openness to experience), and depersonalization (also see Ross, Ellason, & Anderson, 1995; Sanders & Green, 1994)—and others (Ray & Faith, 1994) have identified four factors. In contrast, Waller (1995) reanalyzed Carlson et al.’s (1991) data and concluded that their three-factor solution could reflect the skewed distribution of the items, and thus might be a statistical artifact reflecting the presence of difficulty factors (that is, factors induced by similar levels of skewness across the items; see also Holmes et al., 2005; Wright & Loftus, 1999). Waller, Putnam, and Carlson (1996) responded to criticisms that the DES contains a substantial number of nonpathological items that tap absorption (e.g., “Some people find that when they are watching television or a movie they become so absorbed in the story that they are unaware of other events happening around them.”) by developing the DES-Taxon (DES-T) scale. This 8-item scale contains items from the original DES that measure pathological dissociation, including derealization, depersonalization, psychogenic amnesia, and identity alteration. Waller and Ross (1997) estimated that the general population base rate of pathological dissociation is 3.3%. Of course, being classified as a taxon member (i.e., distinct type or latent class) cannot be equated with DID (Modestin & Erni, 2004), as the prevalence of DID in the general population is almost certainly much lower than 3%. Although the resulting scale was stricter in the criteria for establishing evidence of pathologic dissociation, the data supporting its validity are mixed. Simeon and colleagues (Simeon et al., 1998) found that the DES-T sum score is superior to the standard DES at distinguishing patients with depersonalization disorders (DDD) from control subjects. Nevertheless, later studies revealed that the DES-T: (a) classified only 64% of patients with DDD as having a dissociative disorder (Simeon et al., 2003), (b) produced high false positive rates (Giesbrecht, Merckelbach, & Geraerts, 2007), and (c) lacked temporal stability for taxon membership probability (Watson, 2003). Nevertheless, many studies have documented significant differences between people who score high versus low on both the DES and the DES-T with respect to a variety of measures of memory and cognition (Giesbrecht et al., 2008). The Adolescent Dissociative Experiences Scale (A-DES; Armstrong, Putnam, Carlson, Libero, & Smith, 1997) is a 30-item self-report measure designed exclusively for use with adolescent populations. The scale is intended to serve as a screening tool for dissociative disorders among adolescents and trace the developmental trajectories of normal and pathological dissociation over time. The A-DES items are rated on an 11-point Likert-type scale, and comprise the following subscales: dissociative amnesia, absorption and imaginative involvement, passive influence, and depersonalization and derealization. The A-DES was normed using a group of healthy adolescents in junior-high and high school populations (Smith & Carlson, 1996) and a group of adolescent clinical patients (Armstrong et al., 1997). The authors reported excellent internal consistency for the total score (α = .93) and subscales (α = .72–85). Nevertheless, there are questions concerning the A-DES’s convergent validity. In a sample of 331 nonreferred youths, Muris, Merckelbach, and Peeters (2003) reported that A-DES scores are not only significantly related to PTSD symptoms and fantasy proneness, but also to other anxiety symptoms. The Multidimensional Inventory of Dissociation (MID 5.0; Dell, 2006) is a recently developed self-report measure created to assess the symptom-domain of DID and the phenomenological domain of dissociation. The MID 5.0 contains 168 dissociation items and 50 validity items rated on a 0–10 Likert-type scale. The MID shows promising convergent validity with other psychiatric diagnoses (e.g., it distinguishes among individuals with DID, dissociative disorder not otherwise specified, mixed psychiatric, and nonclinical adults; Dell, 2002) and self-report measures (e.g., correlations with the DES = .90; Dell, 2006), as well as structural validity (e.g., factor analyses isolated a single overarching factor of pathological dissociation; see Dell, 2006). Nevertheless, these findings have yet to be replicated by independent research groups. The author reported good-to-excellent internal consistency of the 23 dissociation scales (α = 0.84–0.96) and temporal stability (4- to 8-week test-retest interval; rs = .82–.97) in a large clinical sample. These latter results were replicated in Israel and Germany (see Dell, 2006). The Somatoform Dissociation Questionnaire (SDQ-20; Nijenhuis, Spinhoven, Van Dyck, Van der Hart, & Vanderlinden, 1996) is a self-report measure designed to evaluate the presence of somatoform responses associated with dissociative states that cannot be medically explained. Participants rate items on a 5-point Likert-type scale. Twenty of the 75 original items discriminated outpatients with dissociative disorders from nondissociative psychiatric outpatients and comprised the final scale. The authors reported excellent internal consistency (α = 0.95) and higher scores among patients with DID compared with patients with dissociative disorder not otherwise specified. The authors also reduced the SDQ-20 to a five-item screen for dissociative disorders (SDQ-5; Nijenhuis, Spinhoven, Van Dyck, Van der Hart, & Vanderlinden, 1997). For dissociative disorders among psychiatric patients, the SDQ-5 exhibited a sensitivity of 94% and a specificity of 98% (Nijenhuis et al., 1998). A study in which DES, MID, and SDQ-20 were compared to SCID-D outcomes in psychiatric outpatients found that these self-report instruments have comparable diagnostic accuracy and are equivalently suitable as screening tools for dissociative disorders (Mueller-Pfeiffer et al., 2013). The Dissociation Questionnaire (DIS-Q; Vanderlinden, Van Dyck, Vandereycken, & Vertommen, 1991) was developed to account for sociocultural differences in European populations as well as to assess a broad spectrum of dissociative experiences. The authors generated items from existing dissociation questionnaires and clinical experience. Participants rate items on a 1–5 Likert-type scale; the final 63-item scale was normed on 374 participants from the general population in Belgium and the Netherlands. Four factors constitute the DIS-Q (i.e., identity confusion, loss of control, amnesia, and absorption). Internal consistency of the subscales (α = 0.67–0.94) and the overall scale (α = 0.96) were good to excellent, as was test-retest reliability over a period of 3–4 weeks. The authors report successful discrimination of patients with dissociative disorders and nondissociative disorders with the exception of PTSD. Within the dissociative disorders, the DIS-Q successfully discriminated DID from dissociative disorder–not otherwise specified. The State Scale of Dissociation (SSD; Kruger & Mace, 2002) is a self-report inventory designed to detect changes in dissociative states, rather than traits. The SSD was developed using existing scales, the DSM-IV, and the ICD-10, along with the aid of clinical experts. The 56-item scale is scored on a Likert-type scale from 0–9 and broken down into seven subscales: derealization, depersonalization, identity confusion, identity alteration, conversion, amnesia, and hypermnesia (remembering things too well). In the original study, the SSD was administered to 130 patients with major depression (n = 19), schizophrenia (n = 18), alcohol withdrawal (n = 20), dissociative disorders (n = 10), and healthy controls (n = 63). A score of > 3.9 nearly doubled the certainty of a diagnosis of a dissociative disorder, although an important limitation is the small sample of dissociative patients. The internal consistency of the SSD was good to excellent for the total scale (α = 0.97), and correlations between the SSD and the DES among people with a dissociative disorder were r = .81, and r = .57 in healthy controls. Following a brief grounding activity (53 minutes, during which participants completed a number of other scales), the SSD scores among all participants decreased significantly on retest, suggesting that the SSD is sensitive to short-term changes in dissociative states across diagnostic groups. The Cambridge Depersonalization Scale (CDS; Sierra & Berrios, 2000) consists of 29 items that ask respondents to rate recent depersonalization symptoms on a 5-point frequency scale (anchors: 0 = never; 4 = all the time) and a 6-point duration scale (anchors: 1 = few seconds; 6 = more than a week). The scale differentiates patients with DDD from other patient groups (e.g., patients with epilepsy, anxiety disorders) and from healthy controls (Sierra & Berrios, 2000). Sierra and Berrios (2000, 2001) reported sound internal consistency for the CDS (e.g., α = 0.89). An exploratory factor analysis identified four factors that accounted for 73.3% of the variance: anomalous body experience, emotional numbing, anomalous subjective recall, and alienation from surroundings (Sierra et al., 2005). Assessment is often an ongoing process in psychotherapy, and much information can be gleaned in the absence of standardized tests of dissociative experiences and symptoms. In this regard, a number of caveats are in order. Less formal assessment procedures that even subtly suggest a history of abuse or validate the manifestation of alters with separate histories (e.g., personality “system mapping” to establish contact with nonforthcoming alters, providing names to alters, prompting or suggesting the emergence appearance of alters) should be avoided. A concern is that therapists who repeatedly ask leading questions such as “Is it possible that there is another part of you with whom I haven’t yet spoken?” may elicit via suggestion imagined-believed-in alter personalities that ostensibly account for their clients’ otherwise enigmatic behaviors (e.g., self-mutilation, and rapid and intense mood shifts). Repeated questioning about historical events is not helpful, as it can lead patients to mistakenly believe that they have significant gaps (e.g., amnesia) in their autobiographical memories of childhood (Belli, Winkielman, Read, Schwartz, & Lynn, 1998; Read & Lindsay, 2000). Assessors should also eschew the use of hypnosis to recover allegedly dissociated or repressed memories given that hypnosis does not enhance the overall accuracy of memories and is associated with a heightened risk for confabulation (Lynn, Knox, Fassler, Lilienfeld, & Loftus, 2004). The patient, a 47-year old Caucasian female, first presented with dissociative symptoms to a health professional during a routine pelvic examination (see Colletti, Lynn, & Laurence, 2010 for a more complete description). During the exam, she exhibited dramatic changes in her demeanor. In quick succession, her emotions vacillated unpredictably, ranging from calm and composed, to scared and vulnerable, to angry and aggressive. The physician referred her for psychotherapy, insofar as her histrionic presentation was at sharp variance with what he observed during prior office visits. When the patient initiated treatment with a psychotherapist, she insisted that her problems were the product of stress at work related to serious medical concerns (e.g., lupus, peripheral neuralgia, among others) that interfered with her job performance. Nevertheless, the therapist, a graduate student at a psychological clinic, noted that her mood and behavior fluctuated dramatically both within and between sessions, with episodes of anger and anxiety flaring up frequently and unpredictably within sessions. Over the next 2 years, the patient recounted a history of sexual assault 7 years prior to treatment, the death of a sibling, intense and sometimes unstable interpersonal relationships, and sexual abuse in childhood. Emotional outbursts during sessions escalated; seemingly innocuous statements by the therapist could trigger memories of highly aversive events. The patient began to experience more frequent crises in and out of sessions as well as emotional lability, often alternating between speaking in a childlike voice and an angry adult, only to later apologize and express deep regret. Her memory for what transpired when she appeared to be enacting different “identities” was spotty and at times devoid of meaningful content. After 2 years of treatment, the graduate student transferred the case to his supervisor, who witnessed increased irritability, vitriolic anger, and flashback-like experiences in session that were followed by amnesia, depersonalization, derealization, and problems in focusing attention. The patient reported feeling “spaced out” in session, and reported that she often was aware of “missing time” at home, and experienced difficulties recalling anything beyond the gist of the previous session. At the start of treatment with her second therapist, she met the criteria for borderline personality disorder, and DID was considered a rule-out diagnosis. She reported hearing “voices in my head” and experienced herself as “splitting off” into an angry “adult protector” or defender of others and childlike aspects of herself that required protection. One major diathesis for her dissociative symptoms appeared to be a history of fantasy versus reality-based coping originating in childhood. She became aware of this style of coping when her sister died when the patient was 5 years old, and she experienced guilt for not somehow preventing her death. She stated that she began, from that time forward, to think of herself as split into angry and protective “parts.” As therapy progressed, she reported more frequent episodes of depersonalization and disturbing episodes of amnesia, as well as disorientation at times of high stress. She also reported more incidents of abuse during childhood, and her therapist felt her presentation now met criteria for DID.
Dissociative Disorders
Dissociative Amnesia
Epidemiology
Dissociative Fugue
Diagnostic Considerations
Epidemiology
Depersonalization/Derealization Disorder
Diagnostic Considerations
Epidemiology
Dissociative Identity Disorder
Diagnostic Considerations
Epidemiology
Psychological Assessment
Structured Interview Measures
Self-Report Measures
Case Example
Case Identification and Presenting Complaints
History
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