What disorder is occurring when a person seems to have two or more distinct personalities or identities within one body?

Reviewed by Psychology Today Staff

Dissociative identity disorder, formerly referred to as multiple personality disorder, is characterized by a person's identity fragmenting into two or more distinct personality states. People with this condition are often victims of severe abuse.

Dissociative identity disorder (DID) is a rare condition in which two or more distinct identities, or personality states, are present in—and alternately take control of—an individual. Some people describe this as an experience of possession. The person also experiences memory loss that is too extensive to be explained by ordinary forgetfulness.

DID was called multiple personality disorder up until 1994 when the name was changed to reflect a better understanding of the condition—namely, that it is characterized by fragmentation or splintering of identity, rather than by proliferation or growth of separate personalities. The symptoms of DID cannot be explained away as the direct psychological effects of a substance or of a general medical condition.

DID reflects a failure to integrate various aspects of identity, memory, and consciousness into a single multidimensional self. Usually, a primary identity carries the individual's given name and is passive, dependent, guilty, and depressed. When in control, each personality state, or alter, may be experienced as if it has a distinct history, self-image, and identity. The alters' characteristics—including name, reported age and gender, vocabulary, general knowledge, and predominant mood—contrast with those of the primary identity. Certain circumstances or stressors can cause a particular alter to emerge. The various identities may deny knowledge of one another, be critical of one another, or appear to be in open conflict.

article continues after advertisement

According to the DSM-5, the following criteria must be met for an individual to be diagnosed with dissociative identity disorder:

• The individual experiences two or more distinct identities or personality states (each with its own enduring pattern of perceiving, relating to, and thinking about the environment and self). Some cultures describe this as an experience of possession.
• The disruption in identity involves a change in sense of self, sense of agency, and changes in behavior, consciousness, memory, perception, cognition, and motor function.
• Frequent gaps are found in the individual’s memories of personal history, including people, places, and events, for both the distant and recent past. These recurrent gaps are not consistent with ordinary forgetting.
• The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.

Particular identities may emerge in specific circumstances. Transitions from one identity to another are often triggered by emotional stress. In the possession-form of dissociative identity disorder, alternate identities are visibly obvious to people around the individual. In non-possession-form cases, most individuals do not overtly display their change in identity for long periods of time.

People with DID may describe feeling that they have suddenly become depersonalized observers of their own speech and actions. They might report hearing voices (a child's voice or the voice of a spiritual power), and in some cases, the voices accompany multiple streams of thought that the individual has no control over. The individual might also experience sudden impulses or strong emotions that they don't feel control or a sense of ownership over. People may also report that their bodies suddenly feel different (like that of a small child or someone huge and muscular) or that they experience a sudden change in attitudes or personal preferences before shifting back.

Sometimes people with DID experience dissociative fugue in which they discover, for example, that they have traveled, but have no recollection of the experience. They vary in their awareness of their amnesia, and it is common for people with DID to minimize their amnestic symptoms, even when the lapses in memory are obvious and distressing to others.

In many parts of the world, possession states are a normal part of cultural or spiritual practice. Possession-like identities often manifest as behaviors under the control of a spirit or other supernatural being. Possession states become a disorder only when they are unwanted, cause distress or impairment, and are not accepted as part of cultural or religious practice. 

According to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, more than 70 percent of people with DID have attempted suicide at least once, and self-injurious behavior is common among this group. Treatment is crucial to improving quality of life and preventing suicide attempts for those with DID. 

Why some people develop dissociative identity disorder is not entirely understood, but they frequently report having experienced severe physical and sexual abuse during childhood.

The disorder may first manifest at any age. Individuals with DID may have post-traumatic symptoms (nightmares, flashbacks, or startle responses) or post-traumatic stress disorder. Several studies suggest that DID is more common among close biological relatives of persons who also have the disorder than in the general population.

Once a rarely reported disorder, the diagnosis has grown more common—and controversial. Some experts contend that because DID patients are highly suggestible, their symptoms are at least partly iatrogenic—that is, prompted by their therapists' probing. Brain imaging studies, however, have corroborated identity transitions.

There are other dissociative disorders, all of which concern an individual's disconnection with reality. The person who suffers dissociative amnesia, for example, has difficulty remembering who they are, where they live, and other important personal information. And the person who suffers depersonalized or derealization disorder is detached from their actions.

The primary treatment for dissociative identity disorder is long-term psychotherapy with the goal of deconstructing the different personalities and integrating them into one. Other treatments include cognitive and creative therapies. Although there are no medications that specifically treat this disorder, antidepressants, anti-anxiety drugs, or tranquilizers may be prescribed to help control the psychological symptoms associated with it. With proper treatment, many people who are impaired by DID experience improvement in their ability to function in their work and personal lives.

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition.

National Institute of Mental Health