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Dissociative Identity Disorder

(Multiple Personality Disorder)

By David Spiegel, MD, Jack, Lulu and Sam Willson, Stanford School of Medicine

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In dissociative identity disorder, formerly called multiple personality disorder, two or more identities alternate being in control within the same person. Also, the person cannot recall information that would ordinarily be readily remembered, such as everyday events, important personal information, and/or traumatic or stressful events.

  • Extreme stress during childhood may prevent some children from integrating their experiences into one cohesive identity.

  • People have two or more identities and have gaps in their memory for everyday events, important personal information, and traumatic or stressful events, as well as many other symptoms, including depression and anxiety.

  • A thorough psychiatric interview and special questionnaires, sometimes facilitated by hypnosis or sedatives, help doctors diagnose the disorder.

  • Extensive psychotherapy may help people integrate their identities or at least help the identities cooperate.

How many people have dissociative identity disorder is unknown. In one study, about 1.5% people had the disorder in a given year.

Dissociative identity disorder has the following forms:

  • Possession

  • Nonpossession

In the possession form, the person's different identities appear as though they were an outside agent who has taken control of the person. This outside agent may be described as a supernatural being or spirit but sometimes is another person. In all cases, people speak and act very differently from the way they normally do. Thus, the different identities are obvious to other people. In many cultures, similar possession states are a normal part of the local culture or religion and are not considered a disorder. In contrast, in dissociative identity disorder, the alternate identity is unwanted, causes substantial distress and impairment, and appears in times and places that are inappropriate for the person's social situation, culture, and/or religion.

Nonpossession forms tend to be less apparent to others. People may feel a sudden alteration in their sense of self, perhaps feeling as though they were observers of their own speech, emotions, and actions, rather than the agent.

Causes of Dissociative Identity Disorder

Dissociative identity disorder usually occurs in people who experienced overwhelming stress during childhood. In the United States, Canada, and Europe, about 90% of people with this disorder had been severely abused (physically, sexually, or emotionally) or neglected when they were children.

As children develop, they must learn to integrate complicated and different types of information and experiences into a cohesive, complex personal identity. Sexual and physical abuse that occurs in childhood when personal identity is developing may have lasting effects on the person's ability to form a single, unified identity, especially when the abusers are parents or caregivers. However, if such vulnerable children are sufficiently protected and soothed by truly caring adults, dissociative identity disorder is less likely to develop.

Symptoms of Dissociative Identity Disorder

Dissociative identity disorder is chronic and potentially disabling, although many people function very well and lead creative and productive lives.

Several symptoms are typical.

More than one identity

People with the disorder may feel detached from aspects of themselves (a condition called depersonalization), as if they were watching themselves in a movie or as though they were seeing a different person. They may suddenly think, feel, say, and do things that they cannot control and that do not seem to belong to them. Attitudes, opinions, and preferences (for example, regarding food, clothing, or interests) may suddenly change, then change back.

People may think that their body feels different (for example, like that of a small child or someone of the opposite sex) and that their body does not belong to them. They may refer to themselves in the first person plural (we) or in the third person (he, she, they), sometimes without knowing why.

Although these symptoms are subjective, many of them can be observed by others

Some of a person’s personalities are aware of important personal information of which other personalities are unaware. Some personalities appear to know and interact with one another in an elaborate inner world. For example, personality A may be aware of personality B and know what B does, as if observing B’s behavior. Personality B may or may not be aware of personality A, and so on with other personalities present. The switching of personalities and the lack of awareness of the behavior of the other personalities often make life chaotic. Because the identities interact with each other, affected people may report hearing voices. The voices may be internal conversations among the identities or may address the person directly, sometimes commenting on the person's behavior. Several voices may speak at the same time and be very confusing.

People with dissociative identity disorder also experience intrusions of identities, voices, or memories into their everyday activities. For example, at work, an angry identity may suddenly yell at a co-worker or boss.


Amnesia may involve the following:

  • Gaps in the memory of past personal events: For example, people may not remember certain periods of time during childhood or adolescence.

  • Lapses in memory of current everyday events and well-learned skills: For example, people may temporarily forget how to use a computer.

  • Discovery of evidence of things that they have done but have no memory of doing.

People may sense that they are missing a period of time.

After an episode of amnesia, people may discover objects in their closet at home 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. They may not be able to recall things they have done or account for changes in their behavior. They may be told they said or did things that they cannot remember.

Most people cannot recall much about the first 3 to 5 years of life, but people with dissociative identity disorder may not recall much about the period between the ages of 6 and 11 as well.

Other symptoms

People with dissociative identity disorder often describe an array of symptoms that can resemble those of other mental health disorders as well as those of many physical disorders. For example, they often develop severe headaches or other aches and pains. Different groups of symptoms occur at different times. Some of these symptoms may indicate that another disorder is present, but some may reflect the intrusion of past experiences into the present. For example, sadness may indicate coexisting depression, but it also may indicate that one of the personalities is reliving emotions associated with past misfortunes.

Many people with dissociative identity disorder are depressed and anxious. They are prone to injuring themselves. Substance abuse, episodes of self-mutilation, and suicidal behavior (thoughts and attempts) are common, as is sexual dysfunction. Like many people with a history of abuse, they may seek out or stay in dangerous situations and are vulnerable to retraumatization.

In addition to hearing voices of other identities, people may have other types of hallucinations (of sight, touch, smell, or taste). The hallucinations may occur as part of a flashback. Thus, dissociative identity disorder may be misdiagnosed as a psychotic disorder such as schizophrenia. However, these hallucinatory symptoms differ from the typical hallucinations of psychotic disorders. People with dissociative identity disorder experience these symptoms as coming from an alternate identify, from inside their head. People with schizophrenia usually think the source is external, outside of themselves.

Often, people try to play down their symptoms and the effect they have on others.

Diagnosis of Dissociative Identity Disorder

  • A doctor's evaluation

Doctors diagnose dissociative identity disorder based on the person's history.

Doctors conduct a thorough psychiatric interview and use special questionnaires developed to help identify dissociative identity disorder and to rule out other mental health disorders. A physical examination may be needed to determine whether people have a physical disorder that would explain certain symptoms.

Interviews may need to be long and involve careful use of hypnosis or a sedative given intravenously to relax the person (a drug-facilitated interview). People may also be asked to keep a journal between doctor's visits. These measures may allow doctors to encounter other identities or make the person more likely to reveal information about a forgotten period of time.

Doctors may also attempt to directly contact other identities by asking to speak to the part of the mind involved in behaviors that people cannot remember or that seem to be done by someone else.


Some symptoms may come and go spontaneously, but dissociative identity disorder does not clear up on its own.

How well people recover depends on the symptoms and features they have and the quality and duration of treatment they receive. For example, people who have other serious mental health disorders, who do not function well in life, or who remain deeply attached to their abusers do less well. They may require treatment longer, and treatment is less successful.

Treatment of Dissociative Identity Disorder

  • Psychotherapy

  • Sometimes guided imagery and hypnosis

The goal of treatment is usually to integrate the personalities into a single personality. However, integration is not always possible. In these situations, the goal is to achieve a harmonious interaction among the personalities that allows more normal functioning.

Drug therapy can relieve some specific coexisting symptoms, such as anxiety or depression, but does not affect the disorder itself.

Psychotherapy is often long, arduous, and emotionally painful. People may experience many emotional crises from the actions of the identities and from the despair that may occur when traumatic memories are recalled during therapy. Several periods of psychiatric hospitalization may be necessary to help people through difficult times and to come to grips with particularly painful memories. During hospitalization, people are continuously given support and monitored.

Key components of effective psychotherapy for dissociative identity disorder include the following:

  • Providing a way to stabilize intense emotions

  • Negotiating relationships between identity states

  • Working through traumatic memories

  • Protecting against further victimization

  • Establishing and enhancing a good relationship between the person and the therapist

Sometimes psychotherapists use techniques such as hypnosis to help such people calm themselves, alter their perspective on the events, and gradually desensitize the effects of traumatic memories, which are sometimes tolerated only in small amounts.

* This is the Consumer Version. *