(See also Overview of Dissociative Disorders.)
How overt the different identities are varies. They tend to be more overt when people are under extreme stress. The fragmentation of identity usually leads to asymmetric amnesia, in which what is known by one identity may or may not be known by another; ie, one identity may have amnesia for events experienced by other identities. Some identities appear to know and interact with others in an elaborate inner world, and some identities interact more than others.
In one small US community study, the 12-month prevalence of dissociative identity disorder was 1.5%, with men and women affected almost equally (1). The disorder may begin at any age, from early childhood to late life.
Dissociative identity disorder has the following forms:
In the possession form, the identities usually manifest as though they were outside agents, typically a supernatural being or spirit (but sometimes another person), who has taken control of the person, causing the person to speak and act in a very different way. In such cases, the different identities are very overt (readily noticed by others). In many cultures, similar possession states are a normal part of cultural or spiritual practice and are not considered dissociative identity disorder. The possession form that occurs in dissociative identity disorder differs in that the alternate identity is unwanted and occurs involuntarily, it causes substantial distress and impairment, and it manifests in times and places that violate cultural and/or religious norms.
Nonpossession forms tend to be less overt. People may feel a sudden alteration in their sense of self or identity, perhaps feeling as though they were observers of their own speech, emotions, and actions, rather than the agent. Many also have recurrent dissociative amnesia.
Dissociative identity disorder usually occurs in people who experienced overwhelming stress or trauma during childhood.
Children are not born with a sense of a unified identity; it develops from many sources and experiences. In overwhelmed children, many parts of what should have blended together remain separate. Chronic and severe abuse (physical, sexual, or emotional) and neglect during childhood are frequently reported by and documented in patients with dissociative identity disorder (in the US, Canada, and Europe, about 90% of patients). Some patients have not been abused but have experienced an important early loss (such as death of a parent), serious medical illness, or other overwhelmingly stressful events.
In contrast to most children who achieve cohesive, complex appreciation of themselves and others, severely mistreated children may go through phases in which different perceptions, memories, and emotions of their life experiences are kept segregated. Over time, such children may develop an increasing ability to escape the mistreatment by “going away"—that is, by detaching themselves from their harsh physical environment—or by retreating into their own mind. Each developmental phase or traumatic experience may be used to generate a different identity.
On standardized tests, people with this disorder have high scores for susceptibility to hypnosis and dissociation (ability to uncouple one’s memories, perceptions, or identity from conscious awareness).
Several symptoms are characteristic of dissociative identity disorder.
In the possession form, the multiple identities are readily apparent to family members and associates. Patients speak and act in an obviously different manner, as though another person or being has taken over. The new identity may be that of another person (often someone who has died, perhaps in a dramatic fashion) or that of a supernatural spirit (often a demon or god), who may demand punishment for past actions.
In the nonpossession form, the different identities are often not as apparent to observers. Instead, patients experience feelings of depersonalization; ie, they feel unreal, removed from self, and detached from their physical and mental processes. Patients say that they feel like an observer of their life, as if they were watching themselves in a movie over which they have no control (loss of personal agency). They may think that their body feels different (eg, like that of a small child or someone of the opposite sex) and does not belong to them. They may have sudden thoughts, impulses, and emotions that do not seem to belong to them and that may manifest as multiple confusing thought streams or as voices. Some manifestations may be noticed by observers. For example, patients' attitudes, opinions, and preferences (eg, regarding food, clothing, or interests) may suddenly change, then change back.
People with dissociative identity disorder also experience intrusions into their everyday activities when there is a shift in identities or interference by one identity state in the functioning of another. For example, at work, an angry identity may suddenly yell at a co-worker or boss.
Patients typically have dissociative amnesia. It typically manifests as
Gaps in memory of past personal events (eg, periods of time during childhood or adolescence, death of a relative)
Lapses in dependable memory (eg, what happened today, well-learned skills such as how to use a computer)
Discovery of evidence of things that they have done or said but have no memory of doing and/or that seem unlike themselves
Periods of time may be lost.
Patients may discover objects in their shopping bag or samples of handwriting that they cannot account for or recognize. They may also find themselves in different places from where they last remember being and have no idea why or how they got there. Unlike patients with posttraumatic stress disorder, patients with dissociative identity disorder forget everyday events as well as stressful or traumatic ones.
Patients vary in their awareness of the amnesia. Some try to hide it. The amnesia may be noticed by others when patients cannot remember things they have said and done or important personal information, such as their own name.
In addition to hearing voices, patients with dissociative identity disorder may have visual, tactile, olfactory, and gustatory hallucinations. Thus, patients may be misdiagnosed with a psychotic disorder. However, these hallucinatory symptoms differ from the typical hallucinations of psychotic disorders such as schizophrenia. Patients with dissociative identity disorder experience these symptoms as coming from an alternate identity (eg, as if someone else was wanting to cry using their eyes, hearing the voice of an alternate identity criticizing them).
Depression, anxiety, substance abuse, self-injury, self-mutilation, nonepileptic seizures, and suicidal behavior are common, as is sexual dysfunction.
The switching of identities and the amnestic barriers between them frequently result in chaotic lives. Generally, patients try to hide or minimize their symptoms and the effect they have on others.
Diagnosis of dissociative identity disorder is clinical, based on presence of the following criteria in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5):
Patients have ≥ 2 personality states or identities (disruption of identity), with substantial discontinuity in their sense of self and sense of agency.
Patients have gaps in their memory for everyday events, important personal information, and traumatic events—information that would not typically be lost with ordinary forgetting.
Symptoms cause significant distress or significantly impair social or occupational functioning.
Also, the symptoms cannot be better accounted for by another disorder (eg, complex partial seizures, bipolar disorder, posttraumatic stress disorder, another dissociative disorder), by the effects of alcohol intoxication, by broadly accepted cultural or religious practices, or, in children, by fantasy play (eg, an imaginary friend).
The diagnosis requires knowledge of and specific questions about dissociative phenomena. Prolonged interviews, hypnosis, or drug-facilitated (barbiturate or benzodiazepine) interviews are sometimes used, and patients may be asked to keep a journal between visits. All of these measures involve an attempt to bring out a shift of identities during the evaluation. The clinician may over time attempt to map out the different identities and their interrelationships. Specially designed structured interviews and questionnaires can be very helpful, especially for clinicians who have less experience with this disorder.
The clinician may also attempt to directly contact other identities by asking to speak to the part of the mind involved in behaviors that patients cannot remember or that seem to be done by someone else. Hypnosis can help clinicians access the patient's dissociated states and other identities and help the patient better control the shifts among the dissociated states.
Malingering (intentional feigning of physical or psychologic symptoms motivated by an external incentive) should be considered if gain could be a motive (eg, to escape accountability for actions or responsibilities). However, malingerers tend to overreport well-known symptoms of the disorder (eg, dissociative amnesia) and underreport others. They also tend to create stereotypical alternate identities. In contrast to patients who have the disorder, malingerers usually seem to enjoy the idea of having the disorder; in contrast, patients with dissociative identity disorder often try to hide it. When clinicians suspect that the disorder is faked, cross-checking information from multiple sources may detect inconsistencies that preclude the diagnosis.
Impairment in dissociative identity disorder varies widely. It may be minimal in highly functioning patients; in these patients, relationships (eg, with their children, spouse, or friends) may be impaired more than occupational functioning. With treatment, relational, social, and occupational functioning may improve, but some patients respond very slowly to treatment and may need long-term supportive treatment.
Symptoms wax and wane spontaneously, but dissociative identity disorder does not resolve spontaneously. Patients can be divided into groups based on their symptoms:
Symptoms are mainly dissociative and posttraumatic. These patients generally function well and recover completely with treatment.
Dissociative symptoms are combined with prominent symptoms of other disorders, such as personality disorders, mood disorders, eating disorders, and substance abuse disorders. These patients improve more slowly, and treatment may be less successful or longer and more crisis-ridden.
Patients not only have severe symptoms due to coexisting mental disorders but may also remain deeply emotionally attached to their abusers. These patients can be challenging to treat, often requiring longer treatments that typically aim to help control symptoms more than to achieve integration.
Integration of the identity states is the most desirable outcome of treatment of dissociative identity disorder. Drugs are widely used to help manage symptoms of depression, anxiety, impulsivity, and substance abuse but do not relieve dissociation per se.
Treatment to achieve integration centers on psychotherapy. For patients who cannot or will not strive for integration, treatment aims to facilitate cooperation and collaboration among the identities and to reduce symptoms.
The first priority of psychotherapy is to stabilize patients and ensure safety, before evaluating traumatic experiences and exploring problematic identities and reasons for dissociations. Some patients benefit from hospitalization, during which continuous support and monitoring are provided as painful memories are addressed. Therapists should be vigilant in helping such patients avoid revictimization.
Hypnosis may help with accessing the identities, facilitating communication among them, and stabilizing and interpreting them. Some therapists directly engage and interact with the dissociated identity states in an attempt to facilitate integration of the identity states (1).
Modified exposure techniques can be used to gradually desensitize patients to traumatic memories, which are sometimes tolerated only in small fragments.
As the reasons for dissociations are addressed and worked through, therapy can move toward reconnecting, integrating, and rehabilitating the patient’s alternate selves, relationships, and social functioning. Some integration occurs spontaneously during treatment. Integration can be encouraged by negotiating with and arranging the unification of the identities or can be facilitated using hypnotic suggestion and guided imagery.
Patients who have been traumatized, particularly during childhood, may expect further abuse during therapy and develop complex transference reactions to their therapist. Discussing these understandable feelings is an important component of effective psychotherapy.
1. Myrick AC, Webermann AR, Loewenstein RJ, et al: Six-year follow-up of the treatment of patients with dissociative disorders study. Eur J Psychotraumatol 8(1):1344080, 2017. doi: 10.1080/20008198.2017.1344080.