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Dissociative identity disorder
Other namesMultiple personality disorder, split personality
Dissociative identity disorder.jpg
An artist's interpretation of one person with multiple "dissociated personality states"
SpecialtyPsychiatry
SymptomsAt least two distinct and relatively enduring personality states, trouble remembering certain events
ComplicationsSuicide, self harm
DurationLong-term
CausesChildhood trauma, therapy induced
Diagnostic methodBased on clinical criteria
Differential diagnosisMajor depressive disorder, bipolar disorder, PTSD, psychotic disorder, personality disorder, conversion disorder
TreatmentSupportive care, counselling
Frequency~2% of people

Dissociative identity disorder (DID), previously known as multiple personality disorder, is a mental disorder characterized by at least two distinct and relatively enduring personality states. This is accompanied by memory gaps beyond what would be explained by ordinary forgetfulness. These states alternately show in a person's behavior; presentations, however, are variable. Other problems which often occur in people with DID include borderline personality disorder (BPD), posttraumatic stress disorder (PTSD), depression, substance use disorders, self-harm, or anxiety.

Some professionals believe the cause to be childhood trauma. In about 90% of cases, there is a history of abuse in childhood, while other cases are linked to experiences of war or health problems during childhood. Genetic factors are also believed to play a role. An alternative hypothesis is that it is a by-product of techniques employed by some therapists, especially those using hypnosis. The diagnosis should not be made if the person's condition is better accounted for by substance abuse, seizures, imaginative play in children, or religious practices.

Treatment generally involves supportive care and counselling. The condition usually persists without treatment. It is believed to affect about 2% of the general population and 3% of those admitted to hospitals with mental health problems in Europe and North America. DID is diagnosed about six times more often in females than males. The number of cases increased significantly in the latter half of the 20th century, along with the number of identities claimed by those affected.

DID is controversial within both psychiatry and the legal system. In court cases, it has been used as a rarely successful form of the insanity defense. It is unclear whether increased rates of the disorder are due to better recognition or to sociocultural factors such as media portrayals. A large proportion of diagnoses are associated with a small number of clinicians, which is consistent with the hypothesis that DID may be therapist-induced. The typical presenting symptoms in different regions of the world may also vary depending on how the disorder is depicted by the media.

Definitions

Dissociation, the term that underlies the dissociative disorders including DID, lacks a precise, empirical, and generally agreed upon definition. A large number of diverse experiences have been termed dissociative, ranging from normal failures in attention to the breakdowns in memory processes characterized by the dissociative disorders. Thus it is unknown if there is a common root underlying all dissociative experiences, or if the range of mild to severe symptoms is a result of different etiologies and biological structures. Other terms used in the literature, including personality, personality state, identity, ego state and amnesia, also have no agreed upon definitions. Multiple competing models exist that incorporate some non-dissociative symptoms while excluding dissociative ones. The most widely used model of dissociation conceptualizes DID as at one extreme of a continuum of dissociation, with flow at the other end, though this model is being challenged.

Some terms have been proposed regarding dissociation. Psychiatrist Paulette Gillig draws a distinction between an "ego state" (behaviors and experiences possessing permeable boundaries with other such states but united by a common sense of self) and the term "alters" (each of which may have a separate autobiographical memory, independent initiative and a sense of ownership over individual behavior) commonly used in discussions of DID. Ellert Nijenhuis and colleagues suggest a distinction between personalities responsible for day-to-day functioning (associated with blunted physiological responses and reduced emotional reactivity, referred to as the "apparently normal part of the personality" or ANP) and those emerging in survival situations (involving fight-or-flight responses, vivid traumatic memories and strong, painful emotions, the "emotional part of the personality" or EP). "Structural dissociation of the personality" is used by Otto van der Hart and colleagues to distinguish dissociation they attribute to traumatic or pathological causes, which in turn is divided into primary, secondary and tertiary dissociation. According to this hypothesis, primary dissociation involves one ANP and one EP, while secondary dissociation involves one ANP and at least two EPs and tertiary dissociation, which is unique to DID, is described as having at least two ANP and at least two EP. Others have suggested dissociation can be separated into two distinct forms, detachment and compartmentalization, the latter of which, involving a failure to control normally controllable processes or actions, is most evident in DID. Efforts to psychometrically distinguish between normal and pathological dissociation have been made, but they have not been universally accepted.

Signs and symptoms

According to the fifth Diagnostic and Statistical Manual of Mental Disorders (DSM-V), DID symptoms include "the presence of two or more distinct personality states" accompanied by the inability to recall personal information, beyond what is expected through normal forgetfulness. Other DSM-V symptoms include a loss of identity as related to individual distinct personality states, and loss referring to time, sense of self and consciousness. In each individual, the clinical presentation varies and the level of functioning can change from severely impaired to adequate. The symptoms of dissociative amnesia are subsumed under the DID diagnosis but can be diagnosed separately. Individuals with DID may experience distress from both the symptoms of DID (intrusive thoughts or emotions) and the consequences of the accompanying symptoms (dissociation rendering them unable to remember specific information). The majority of patients with DID report childhood sexual or physical abuse, though the accuracy of these reports is controversial. Identities may be unaware of each other and compartmentalize knowledge and memories, resulting in chaotic personal lives. Individuals with DID may be reluctant to discuss symptoms due to associations with abuse, shame, and fear. DID patients may also frequently and intensely experience time disturbances.

Around half of people with DID have fewer than 10 identities and most have fewer than 100; as many as 4,500 have been reported. The average number of identities has increased over the past few decades, from two or three to now an average of approximately 16. However, it is unclear whether this is due to an actual increase in identities, or simply that the psychiatric community has become more accepting of a high number of compartmentalized memory components. The primary identity, which often has the patient's given name, tends to be "passive, dependent, guilty and depressed" with other personalities being more active, aggressive or hostile, and often containing a current time line that lacks childhood memory. Most identities are of ordinary people, though historical, fictional, mythical, celebrity and animal identities have been reported.

Comorbid disorders

The psychiatric history frequently contains multiple previous diagnoses of various disorders and treatment failures. The most common presenting complaint of DID is depression, with headaches being a common neurological symptom. Comorbid disorders can include substance abuse, eating disorders, anxiety, post traumatic stress disorder (PTSD), and personality disorders. A significant percentage of those diagnosed with DID have histories of borderline personality disorder and bipolar disorder. Further, data supports a high level of psychotic symptoms in individuals with DID, and that both individuals diagnosed with schizophrenia and those diagnosed with DID have histories of trauma. Other disorders that have been found to be comorbid with DID are somatization disorders, major depressive disorder, as well as history of a past suicide attempt, in comparison to those without a DID diagnosis. Individuals diagnosed with DID demonstrate the highest hypnotizability of any clinical population. The large number of symptoms presented by individuals diagnosed with DID has led some clinicians to suggest that, rather than being a separate disorder, diagnosis of DID is actually an indication of the severity of the other disorders diagnosed in the patient.

Borderline personality disorder

The DSM-IV-TR states that acts of self-mutilation, impulsivity, and rapid changes in interpersonal relationships "may warrant a concurrent diagnosis of borderline personality disorder." Steven Lynn and colleagues have suggested that the significant overlap between BPD and DID may be a contributing factor to the development of therapy induced DID, in that the suggestion of hidden alters by therapists who propose a diagnosis of DID provides an explanation to patients for the behavioral instability, self-mutilation, unpredictable mood changes and actions they experience. In 1993 a group of researchers reviewed both DID and borderline personality disorder (BPD), concluding that DID was an epiphenomenon of BPD, with no tests or clinical description capable of distinguishing between the two. Their conclusions about the empirical proof of DID were echoed by a second group, who still believed the diagnosis existed, but while the knowledge to date did not justify DID as a separate diagnosis, it also did not disprove its existence. Reviews of medical records and psychological tests indicated that the majority of DID patients could be diagnosed with BPD instead, though about a third could not, suggesting that DID does exist but may be over-diagnosed. Between 50 and 66% of patients also meet the criteria for BPD, and nearly 75% of patients with BPD also meet the criteria for DID, with considerable overlap between the two conditions in terms of personality traits, cognitive and day-to-day functioning, and ratings by clinicians. Both groups also report higher rates of physical and sexual abuse than the general population, and patients with BPD also score highly on measures of dissociation. Even using strict diagnostic criteria, it can be difficult to distinguish between dissociative disorders and BPD (as well as bipolar disorder and schizophrenia), though the presence of comorbid anxiety disorders may help.

Causes

The cause of DID is unknown and widely debated, with debate occurring between supporters of different hypotheses: that DID is a reaction to trauma; that DID is produced by inappropriate psychotherapeutic techniques that cause a patient to enact the role of a patient with DID; and newer hypotheses involving memory processing that allows for the possibility that trauma-induced dissociation can occur after childhood in DID, as it does in PTSD. It has been suggested that all the trauma-based and stress-related disorders be placed in one category that would include both DID and PTSD. Disturbed and altered sleep has also been suggested as having a role in dissociative disorders in general and specifically in DID, alterations in environments also largely affecting the DID patient.

Research is needed to determine the prevalence of the disorder in those who have never been in therapy, and the prevalence rates across cultures. These central issues relating to the epidemiology of DID remain largely unaddressed despite several decades of research. The debates over the causes of DID also extend to disagreements over how the disorder is assessed and treated.

Developmental trauma

People diagnosed with DID often report that they have experienced severe physical and sexual abuse, especially during early to mid-childhood (although the accuracy of these reports has been disputed), and others report an early loss, serious medical illness or other traumatic event. They also report more historical psychological trauma than those diagnosed with any other mental illness. Severe sexual, physical, or psychological trauma in childhood has been proposed as an explanation for its development; awareness, memories and emotions of harmful actions or events caused by the trauma are removed from consciousness, and alternate personalities or subpersonalities form with differing memories, emotions and behavior. DID is attributed to extremes of stress or disorders of attachment. What may be expressed as post-traumatic stress disorder (PTSD) in adults may become DID when occurring in children, possibly due to their greater use of imagination as a form of coping. Possibly due to developmental changes and a more coherent sense of self past the age of six, the experience of extreme trauma may result in different, though also complex, dissociative symptoms and identity disturbances. A specific relationship between childhood abuse, disorganized attachment, and lack of social support are thought to be a necessary component of DID. Other suggested explanations include insufficient childhood nurturing combined with the innate ability of children in general to dissociate memories or experiences from consciousness.

Delinking early trauma from the etiology of dissociation has been explicitly rejected by those supporting the early trauma model. However, a 2012 review article supports the hypothesis that current or recent trauma may affect an individual's assessment of the more distant past, changing the experience of the past and resulting in dissociative states. Giesbrecht et al. have suggested there is no actual empirical evidence linking early trauma to dissociation, and instead suggest that problems with neuropsychological functioning, such as increased distractibility in response to certain emotions and contexts, account for dissociative features. A middle position hypothesizes that trauma, in some situations, alters neuronal mechanisms related to memory. Evidence is increasing that dissociative disorders are related both to a trauma history and to "specific neural mechanisms". It has also been suggested that there may be a genuine but more modest link between trauma and DID, with early trauma causing increased fantasy-proneness, which may in turn render individuals more vulnerable to socio-cognitive influences surrounding the development of DID. Another suggestion made by Hart indicates that there are triggers in the brain that can be the catalyst for different self-states, and that victims of trauma are more susceptible to these triggers than non-victims of trauma; these triggers are said to be related to DID.

The suggestion that DID was the result of childhood trauma increased the appeal of the diagnosis among health care providers, patients and the public as it validated the idea that child abuse had lifelong, serious effects. There is very little experimental evidence supporting the trauma-dissociation hypothesis, and no research showing that dissociation consistently links to long-term memory disruption.

Therapist-induced

The prevailing post-traumatic model of dissociation and dissociative disorders is contested. It has been hypothesized that symptoms of DID may be created by therapists using techniques to "recover" memories (such as the use of hypnosis to "access" alter identities, facilitate age regression or retrieve memories) on suggestible individuals. Referred to as the "sociocognitive model" (SCM), it proposes that DID is due to a person consciously or unconsciously behaving in certain ways promoted by cultural stereotypes, with unwitting therapists providing cues through improper therapeutic techniques. This behavior is enhanced by media portrayals of DID.

Proponents of the SCM note that the bizarre dissociative symptoms are rarely present before intensive therapy by specialists in the treatment of DID who, through the process of eliciting, conversing with and identifying alters, shape, or possibly create the diagnosis. While proponents note that DID is accompanied by genuine suffering and the distressing symptoms, and can be diagnosed reliably using the DSM criteria, they are skeptical of the traumatic etiology suggested by proponents. The characteristics of people diagnosed with DID (hypnotizability, suggestibility, frequent fantasization and mental absorption) contributed to these concerns and those regarding the validity of recovered memories of trauma. Skeptics note that a small subset of doctors are responsible for diagnosing the majority of individuals with DID. Psychologist Nicholas Spanos and others have suggested that in addition to therapy caused cases, DID may be the result of role-playing rather than alternative identities, though others disagree, pointing to a lack of incentive to manufacture or maintain separate identities and point to the claimed histories of abuse. Other arguments that therapy can cause DID, include the lack of children diagnosed with DID, the sudden spike in rates of diagnosis after 1980 (although DID was not a diagnosis until DSM-IV, published in 1994), the absence of evidence of increased rates of child abuse, the appearance of the disorder almost exclusively in individuals undergoing psychotherapy, particularly involving hypnosis, the presences of bizarre alternate identities (such as those claiming to be animals or mythological creatures) and an increase in the number of alternate identities over time (as well as an initial increase in their number as psychotherapy begins in DID-oriented therapy.) These various cultural and therapeutic causes occur within a context of pre-existing psychopathology, notably borderline personality disorder, which is commonly comorbid with DID. In addition, presentations can vary across cultures, such as Indian patients who only switch alters after a period of sleep — which is commonly how DID is presented by the media within that country.

The therapy-caused cases of DID, it is argued, are strongly linked to false memory syndrome, a concept and term coined by members of the False Memory Syndrome Foundation in reaction to memories of abuse they allege were recovered by a range of controversial therapies whose effectiveness is unproven. Such a memory could be used to make a false allegation of child sexual abuse. There is little agreement between those who see therapy as a cause and trauma as a cause. Supporters of therapy as a cause of DID suggest that a small number of clinicians diagnosing a disproportionate number of cases would provide evidence for their position though it has also been claimed that higher rates of diagnosis in specific countries like the United States may be due to greater awareness of DID. Lower rates in other countries may be due to an artificially low recognition of the diagnosis. However, false memory syndrome per se is not regarded by mental health experts as a valid diagnosis, and has been described as "a non-psychological term originated by a private foundation whose stated purpose is to support accused parents", and critics argue that the concept has no empirical support, and furthermore describe the False Memory Syndrome Foundation as an advocacy group that has distorted and misrepresented research into memory.

Children

DID is rarely diagnosed in children, despite the average age of appearance of the first alter being three years. This fact is cited as a reason to doubt the validity of DID, and proponents of both etiologies believe that the discovery of DID in a child that had never undergone treatment would critically undermine the SCM. Conversely, if children are found to only develop DID after undergoing treatment it would challenge the traumagenic model. As of 2011, approximately 250 cases of DID in children have been identified, though the data does not offer unequivocal support for either theory. While children have been diagnosed with DID before therapy, several were presented to clinicians by parents who were themselves diagnosed with DID; others were influenced by the appearance of DID in popular culture or due to a diagnosis of psychosis due to hearing voices—a symptom also found in DID. No studies have looked for children with DID in the general population, and the single study that attempted to look for children with DID not already in therapy did so by examining siblings of those already in therapy for DID. An analysis of diagnosis of children reported in scientific publications, 44 case studies of single patients were found to be evenly distributed (i.e., each case study was reported by a different author) but in articles regarding groups of patients, four researchers were responsible for the majority of the reports.

The initial theoretical description of DID was that dissociative symptoms were a means of coping with extreme stress (particularly childhood sexual and physical abuse), but this belief has been challenged by the data of multiple research studies. Proponents of the traumagenic hypothesis claim the high correlation of child sexual and physical abuse reported by adults with DID corroborates the link between trauma and DID. However, the DID-maltreatment link has been questioned for several reasons. The studies reporting the links often rely on self-report rather than independent corroborations, and these results may be worsened by selection and referral bias. Most studies of trauma and dissociation are cross-sectional rather than longitudinal, which means researchers can not attribute causation, and studies avoiding recall bias have failed to corroborate such a causal link. In addition, studies rarely control for the many disorders comorbid with DID, or family maladjustment (which is itself highly correlated with DID). The popular association of DID with childhood abuse is relatively recent, occurring only after the publication of Sybil in 1973. Most previous examples of "multiples" such as Chris Costner Sizemore, whose life was depicted in the book and film The Three Faces of Eve, disclosed no history of child abuse.

Diagnosis

The fourth, revised edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) diagnoses DID according to the diagnostic criteria found in section 300.14 (dissociative disorders). It has also been found difficult to diagnose the disorder in the first place, due to there not being a universal agreement of the definition of dissociation. The criteria require that an adult be recurrently controlled by two or more discrete identities or personality states, accompanied by memory lapses for important information that is not caused by alcohol, drugs or medications and other medical conditions such as complex partial seizures. While otherwise similar, the diagnostic criteria for children also specifies symptoms must not be confused with imaginative play. Diagnosis is normally performed by a clinically trained mental health professional such as a psychiatrist or psychologist through clinical evaluation, interviews with family and friends, and consideration of other ancillary material. Specially designed interviews (such as the SCID-D) and personality assessment tools may be used in the evaluation as well. Since most of the symptoms depend on self-report and are not concrete and observable, there is a degree of subjectivity in making the diagnosis. People are often disinclined to seek treatment, especially since their symptoms may not be taken seriously; thus dissociative disorders have been referred to as "diseases of hiddenness".

The diagnosis has been criticized by supporters of therapy as a cause or the sociocognitive hypothesis as they believe it is a culture-bound and often health care induced condition. The social cues involved in diagnosis may be instrumental in shaping patient behavior or attribution, such that symptoms within one context may be linked to DID, while in another time or place the diagnosis could have been something other than DID. Other researchers disagree and argue that the existence of the condition and its inclusion in the DSM is supported by multiple lines of reliable evidence, with diagnostic criteria allowing it to be clearly discriminated from conditions it is often mistaken for (schizophrenia, borderline personality disorder, and seizure disorder). That a large proportion of cases are diagnosed by specific health care providers, and that symptoms have been created in nonclinical research subjects given appropriate cueing has been suggested as evidence that a small number of clinicians who specialize in DID are responsible for the creation of alters through therapy. The condition may be under-diagnosed due to skepticism and lack of awareness from mental health professionals, made difficult due to the lack of specific and reliable criteria for diagnosing DID as well as a lack of prevalence rates due to the failure to examine systematically selected and representative populations.

Screening

Perhaps due to their perceived rarity, the dissociative disorders (including DID) were not initially included in the Structured Clinical Interview for DSM-IV (SCID), which is designed to make psychiatric diagnoses more rigorous and reliable. Instead, shortly after the publication of the initial SCID a freestanding protocol for dissociative disorders (SCID-D) was published. This interview takes about 30 to 90 minutes depending on the subject's experiences. An alternative diagnostic instrument, the Dissociative Disorders Interview Schedule, also exists but the SCID-D is generally considered superior. The Dissociative Disorders Interview Schedule (DDIS) is a highly structured interview that discriminates among various DSM-IV diagnoses. The DDIS can usually be administered in 30–45 minutes.

Other questionnaires include the Dissociative Experiences Scale (DES), Perceptual Alterations Scale, Questionnaire on Experiences of Dissociation, Dissociation Questionnaire, and the Mini-SCIDD. All are strongly intercorrelated and except the Mini-SCIDD, all incorporate absorption, a normal part of personality involving narrowing or broadening of attention. The DES is a simple, quick, and validated questionnaire that has been widely used to screen for dissociative symptoms, with variations for children and adolescents. Tests such as the DES provide a quick method of screening subjects so that the more time-consuming structured clinical interview can be used in the group with high DES scores. Depending on where the cutoff is set, people who would subsequently be diagnosed can be missed. An early recommended cutoff was 15–20. The reliability of the DES in non-clinical samples has been questioned.

Differential diagnoses

People with DID are diagnosed with five to seven comorbid disorders on average—much higher than other mental illnesses.

Due to overlapping symptoms, the differential diagnosis includes schizophrenia, normal and rapid-cycling bipolar disorder, epilepsy, borderline personality disorder, and autism spectrum disorder. Delusions or auditory hallucinations can be mistaken for speech by other personalities. Persistence and consistency of identities and behavior, amnesia, measures of dissociation or hypnotizability and reports from family members or other associates indicating a history of such changes can help distinguish DID from other conditions. A diagnosis of DID takes precedence over any other dissociative disorders. Distinguishing DID from malingering is a concern when financial or legal gains are an issue, and factitious disorder may also be considered if the person has a history of help or attention seeking. Individuals who state that their symptoms are due to external spirits or entities entering their bodies are generally diagnosed with dissociative disorder not otherwise specified rather than DID due to the lack of identities or personality states. Most individuals who enter an emergency department and are unaware of their names are generally in a psychotic state. Although auditory hallucinations are common in DID, complex visual hallucinations may also occur. Those with DID generally have adequate reality testing; they may have positive Schneiderian symptoms of schizophrenia but lack the negative symptoms. They perceive any voices heard as coming from inside their heads (patients with schizophrenia experience them as external). In addition, individuals with psychosis are much less susceptible to hypnosis than those with DID. Difficulties in differential diagnosis are increased in children.

DID must be distinguished from, or determined if comorbid with, a variety of disorders including mood disorders, psychosis, anxiety disorders, PTSD, personality disorders, cognitive disorders, neurological disorders, epilepsy, somatoform disorder, factitious disorder, malingering, other dissociative disorders, and trance states. An additional aspect of the controversy of diagnosis is that there are many forms of dissociation and memory lapses, which can be common in both stressful and nonstressful situations and can be attributed to much less controversial diagnoses. Individuals faking or mimicking DID due to factitious disorder will typically exaggerate symptoms (particularly when observed), lie, blame bad behavior on symptoms and often show little distress regarding their apparent diagnosis. In contrast, genuine people with DID typically exhibit confusion, distress and shame regarding their symptoms and history.

A relationship between DID and borderline personality disorder has been posited, with various clinicians noting overlap between symptoms and behaviors and it has been suggested that some cases of DID may arise "from a substrate of borderline traits". Reviews of DID patients and their medical records concluded that the majority of those diagnosed with DID would also meet the criteria for either borderline personality disorder or more generally borderline personality.

The DSM-5 elaborates on cultural background as an influence for some presentations of DID.
Many features of dissociative identity disorder can be influenced by the individual's cultural background. Individuals with this disorder may present with prominent medically unexplained neurological symptoms, such as non-epileptic seizures, paralyses, or sensory loss, in cultural settings where such symptoms are common. Similarly, in settings where normative possession is common (e.g., rural areas in the developing world, among certain religious groups in the United States and Europe), the fragmented identities may take the form of possessing spirits, deities, demons, animals, or mythical figures. Acculturation or prolonged intercultural contact may shape the characteristics of other identities(e.g., identities in India may speak English exclusively and wear Western clothes). Possession-form dissociative identity disorder can be distinguished from culturally accepted possession states in that the former is involuntary, distressing, uncontrollable, and often recurrent or persistent; involves conflict between the individual and his or her surrounding family, social, or work milieu; and is manifested at times and in places that violate the norms of the culture or religion.

History in the DSM

The DSM-II used the term Hysterical Neurosis, Dissociative Type. It described the possible occurrence of alterations in the patient's state of consciousness or identity, and included the symptoms of "amnesia, somnambulism, fugue, and multiple personality". The DSM-III grouped the diagnosis with the other four major dissociative disorders using the term "multiple personality disorder". The DSM-IV made more changes to DID than any other dissociative disorder, and renamed it DID. The name was changed for two reasons. First, the change emphasizes the main problem is not a multitude of personalities, but rather a lack of a single, unified identity and an emphasis on "the identities as centers of information processing". Second, the term "personality" is used to refer to "characteristic patterns of thoughts, feelings, moods and behaviors of the whole individual", while for a patient with DID, the switches between identities and behavior patterns is the personality. It is for this reason the DSM-IV-TR referred to "distinct identities or personality states" instead of personalities. The diagnostic criteria also changed to indicate that while the patient may name and personalize alters, they lack an independent, objective existence. The changes also included the addition of amnesia as a symptom, which was not included in the DSM-III-R because despite being a core symptom of the condition, patients may experience "amnesia for the amnesia" and fail to report it. Amnesia was replaced when it became clear that the risk of false negative diagnoses was low because amnesia was central to DID.

The ICD-10 places the diagnosis in the category of "dissociative disorders", within the subcategory of "other dissociative (conversion) disorders", but continues to list the condition as multiple personality disorder.

The DSM-IV-TR criteria for DID have been criticized for failing to capture the clinical complexity of DID, lacking usefulness in diagnosing individuals with DID (for instance, by focusing on the two least frequent and most subtle symptoms of DID) producing a high rate of false negatives and an excessive number of DDNOS diagnoses, for excluding possession (seen as a cross-cultural form of DID), and for including only two "core" symptoms of DID (amnesia and self-alteration) while failing to discuss hallucinations, trance-like states, somatoform, depersonalization, and derealization symptoms. Arguments have been made for allowing diagnosis through the presence of some, but not all of the characteristics of DID rather than the current exclusive focus on the two least common and noticeable features. The DSM-IV-TR criteria have also been criticized for being tautological, using imprecise and undefined language and for the use of instruments that give a false sense of validity and empirical certainty to the diagnosis.

The DSM-5 updated the definition of DID in 2013, summarizing the changes as:
Several changes to the criteria for dissociative identity disorder have been made in DSM-5. First, Criterion A has been expanded to include certain possession-form phenomena and functional neurological symptoms to account for more diverse presentations of the disorder. Second, Criterion A now specifically states that transitions in identity may be observable by others or self-reported. Third, according to Criterion B, individuals with dissociative identity disorder may have recurrent gaps in recall for everyday events, not just for traumatic experiences. Other text modifications clarify the nature and course of identity disruptions.

Controversy

DID is among the most controversial of the dissociative disorders and among the most controversial disorders found in the DSM-IV-TR. The primary dispute is between those who believe DID is caused by traumatic stresses forcing the mind to split into multiple identities, each with a separate set of memories, and the belief that the symptoms of DID are produced artificially by certain psychotherapeutic practices or patients playing a role they believe appropriate for a person with DID. The debate between the two positions is characterized by intense disagreement. Research into this hypothesis has been characterized by poor methodology. Psychiatrist Joel Paris notes that the idea that a personality is capable of splitting into independent alters is an unproven assertion that is at odds with research in cognitive psychology.

Some believe that DID is caused by health care, i.e. symptoms of DID are created by therapists themselves via hypnosis. This belief also implies that those with DID are more susceptible to manipulation by hypnosis and suggestion than others. The iatrogenic model also sometimes states that treatment for DID is harmful. According to Brand, Loewenstein and Spiegel, "[t]he claims that DID treatment is harmful are based on anecdotal cases, opinion pieces, reports of damage that are not substantiated in the scientific literature, misrepresentations of the data, and misunderstandings about DID treatment and the phenomenology of DID”. Their claim is evinced by the fact that only 5%–10% of people receiving treatment worsen in their symptoms.

Psychiatrists August Piper and Harold Merskey have challenged the trauma hypothesis, arguing that correlation does not imply causation—the fact that people with DID report childhood trauma does not mean trauma causes DID—and point to the rareness of the diagnosis before 1980 as well as a failure to find DID as an outcome in longitudinal studies of traumatized children. They assert that DID cannot be accurately diagnosed because of vague and unclear diagnostic criteria in the DSM and undefined concepts such as "personality state" and "identities", and question the evidence for childhood abuse beyond self-reports, the lack of definition of what would indicate a threshold of abuse sufficient to induce DID and the extremely small number of cases of children diagnosed with DID despite an average age of appearance of the first alter of three years. Psychiatrist Colin Ross disagrees with Piper and Merskey's conclusion that DID cannot be accurately diagnosed, pointing to internal consistency between different structured dissociative disorder interviews (including the Dissociative Experiences Scale, Dissociative Disorders Interview Schedule and Structured Clinical Interview for Dissociative Disorders) that are in the internal validity range of widely accepted mental illnesses such as schizophrenia and major depressive disorder. In his opinion, Piper and Merskey are setting the standard of proof higher than they are for other diagnoses. He also asserts that Piper and Merskey have cherry-picked data and not incorporated all relevant scientific literature available, such as independent corroborating evidence of trauma.

Pathophysiology

Despite research on DID including structural and functional magnetic resonance imaging, positron emission tomography, single-photon emission computed tomography, event-related potential, and electroencephalography, no convergent neuroimaging findings have been identified regarding DID, making it difficult to hypothesize a biological basis for DID. In addition, many of the studies that do exist were performed from an explicitly trauma-based position, and did not consider the possibility of therapy as a cause of DID. There is no research to date regarding the neuroimaging and introduction of false memories in DID patients, though there is evidence of changes in visual parameters and support for amnesia between alters. DID patients also appear to show deficiencies in tests of conscious control of attention and memorization (which also showed signs of compartmentalization for implicit memory between alters but no such compartmentalization for verbal memory) and increased and persistent vigilance and startle responses to sound. DID patients may also demonstrate altered neuroanatomy. Experimental tests of memory suggest that patients with DID may have improved memory for certain tasks, which has been used to criticize the hypothesis that DID is a means of forgetting or suppressing memory. Patients also show experimental evidence of being more fantasy-prone, which in turn is related to a tendency to over-report false memories of painful events.

Treatment

There is a general lack of consensus in the diagnosis and treatment of DID and research on treatment effectiveness focuses mainly on clinical approaches described in case studies. General treatment guidelines exist that suggest a phased, eclectic approach with more concrete guidance and agreement on early stages but no systematic, empirically-supported approach exists and later stages of treatment are not well described and have no consensus. Even highly experienced therapists have few patients that achieve a unified identity. Common treatment methods include an eclectic mix of psychotherapy techniques, including cognitive behavioral therapy (CBT), insight-oriented therapy, dialectical behavioral therapy (DBT), hypnotherapy and eye movement desensitization and reprocessing (EMDR). Medications can be used for comorbid disorders or targeted symptom relief. Some behavior therapists initially use behavioral treatments such as only responding to a single identity, and then use more traditional therapy once a consistent response is established. Brief treatment due to managed care may be difficult, as individuals diagnosed with DID may have unusual difficulties in trusting a therapist and take a prolonged period to form a comfortable therapeutic alliance. Regular contact (weekly or biweekly) is more common, and treatment generally lasts years—not weeks or months. Sleep hygiene has been suggested as a treatment option, but has not been tested. In general there are very few clinical trials on the treatment of DID, none of which were randomized controlled trials.

Therapy for DID is generally phase oriented. Different alters may appear based on their greater ability to deal with specific situational stresses or threats. While some patients may initially present with a large number of alters, this number may reduce during treatment—though it is considered important for the therapist to become familiar with at least the more prominent personality states as the "host" personality may not be the "true" identity of the patient. Specific alters may react negatively to therapy, fearing the therapist's goal is to eliminate the alter (particularly those associated with illegal or violent activities). A more realistic and appropriate goal of treatment is to integrate adaptive responses to abuse, injury or other threats into the overall personality structure. There is debate over issues such as whether exposure therapy (reliving traumatic memories, also known as abreaction), engagement with alters and physical contact during therapy are appropriate and there are clinical opinions both for and against each option with little high-quality evidence for any position.

Brandt et al., noting the lack of empirical studies of treatment effectiveness, conducted a survey of 36 clinicians expert in treating dissociative disorder (DD) who recommended a three-stage treatment. They agreed that skill building in the first stage is important so the patient can learn to handle high risk, potentially dangerous behavior, as well as emotional regulation, interpersonal effectiveness and other practical behaviors. In addition, they recommended "trauma-based cognitive therapy" to reduce cognitive distortions related to trauma; they also recommended that the therapist deal with the dissociated identities early in treatment. In the middle stage, they recommended graded exposure techniques, along with appropriate interventions as needed. The treatment in the last stage was more individualized; few with DD [sic] became integrated into one identity.

The International Society for the Study of Trauma and Dissociation has published guidelines to phase-oriented treatment in adults as well as children and adolescents that are widely used in the field of DID treatment. The first phase of therapy focuses on symptoms and relieving the distressing aspects of the condition, ensuring the safety of the individual, improving the patient's capacity to form and maintain healthy relationships, and improving general daily life functioning. Comorbid disorders such as substance abuse and eating disorders are addressed in this phase of treatment. The second phase focuses on stepwise exposure to traumatic memories and prevention of re-dissociation. The final phase focuses on reconnecting the identities of disparate alters into a single functioning identity with all its memories and experiences intact.

A study was conducted with the goal of developing an "expertise-based prognostic model for the treatment of complex posttraumatic stress disorder (PTSD) and dissociative identity disorder (DID)". Researchers constructed a two-stage survey and factor analyses performed on the survey elements found 51 factors common to complex PTSD and DID. The authors concluded from their findings: "The model is supportive of the current phase-oriented treatment model, emphasizing the strengthening of the therapeutic relationship and the patient's resources in the initial stabilization phase. Further research is needed to test the model's statistical and clinical validity."

Prognosis

Little is known about prognosis of untreated DID. It rarely, if ever, goes away without treatment, but symptoms may resolve from time to time or wax and wane spontaneously. Patients with mainly dissociative and posttraumatic symptoms face a better prognosis than those with comorbid disorders or those still in contact with abusers, and the latter groups often face lengthier and more difficult treatment. Suicidal ideation, failed suicide attempts, and self-harm also occur. Duration of treatment can vary depending on patient goals, which can range from merely improving inter-alter communication and cooperation, to reducing inter-alter amnesia, to integration of all alters, but generally takes years.

Epidemiology

There is little systematic data on the prevalence of DID. It occurs more commonly in young adults and declines with age. Reported rates in the community vary from 1% to 3% with higher rates among psychiatric patients. It is 5 to 9 times more common in females than males during young adulthood, though this may be due to selection bias as males who could be diagnosed with DID may end up in the criminal justice system rather than hospitals. In children rates among females and males are approximately the same (5:4). DID diagnoses are extremely rare in children; much of the research on childhood DID occurred in the 1980s and 1990s and does not address ongoing controversies surrounding the diagnosis.

Though the condition has been described in non-English speaking nations and non-Western cultures, these reports all occur in English-language journals authored by international researchers who cite Western scientific literature and are therefore not isolated from Western influences.

Changing prevalence

Rates of diagnosed DID were increasing, reaching a peak of approximately 40,000 cases by the end of the 20th century, up from less than 200 before 1970. Initially DID along with the rest of the dissociative disorders were considered the rarest of psychological conditions, numbering less than 100 by 1944, with only one further case added in the next two decades. In the late 1970s and 80s, the number of diagnoses rose sharply. An estimate from the 1980s places the incidence at 0.01%. Accompanying this rise was an increase in the number of alters, rising from only the primary and one alter personality in most cases, to an average of 13 in the mid-1980s (the increase in both number of cases and number of alters within each case are both factors in professional skepticism regarding the diagnosis). Others explain the increase as being due to the use of inappropriate therapeutic techniques in highly suggestible individuals, though this is itself controversial while proponents of DID claim the increase in incidence is due to increased recognition of and ability to recognize the disorder. Figures from psychiatric populations (inpatients and outpatients) show a wide diversity from different countries.

North America

The DSM does not provide an estimate of incidence for DID and dissociative disorders were excluded from the Epidemiological Catchment Area Project. As a result, there are no national statistics for prevalence and incidence of DID in the United States.

DID is a controversial diagnosis and condition, with much of the literature on DID still being generated and published in North America, to the extent that it was once regarded as a phenomenon confined to that continent though research has appeared discussing the appearance of DID in other countries and cultures. A 1996 review offered three possible causes for the sudden increase in people diagnosed with DID:
  1. The result of therapist suggestions to suggestible people, much as Charcot's hysterics acted in accordance with his expectations.
  2. Psychiatrists' past failure to recognize dissociation being redressed by new training and knowledge.
  3. Dissociative phenomena are actually increasing, but this increase only represents a new form of an old and protean entity: "hysteria".
Paris believes that the first possible cause is the most likely. Etzel Cardena and David Gleaves believe the over-representation of DID in North America is the result of increased awareness and training about the condition which had formerly been missing.

History

Early references