Dissociative identity disorder (DID), also known as multiple personality disorder, is a mental disorder characterized by at least two distinct and relatively enduring personality states. There is often trouble remembering certain events, beyond what would be explained by ordinary forgetfulness. These states alternately show in a person’s behavior; presentations, however, are variable. Associated conditions often include borderline personality disorder, post traumatic stress disorder, depression, substance misuse disorder, self-harm or anxiety.
The cause is believed 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. Before a diagnosis is made, it should be verified that the person’s condition is not 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 both within psychiatry and the legal system. In court cases, it has been used as a rarely successful form of the insanity defense. It is unclear if increased rates of the disorder are due to better recognition or sociocultural factors such as media portrayals. A large proportion of diagnoses are clustered around a small number of clinicians, which supports 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.
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-5), 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-5 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.:503 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.
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.
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 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.
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.
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.