What is DID?

When something does not feel like yours

Sometimes a person does something and does not feel like they were the one who chose it. Their voice, posture, skills, feelings, or view of a situation may shift. They may find a message they do not remember writing, though they must have been the one who wrote it.¹

Before diagnosis, there may be no clear explanation for any of this. A thought arrives and feels out of character. A sentence comes out in a tone the person did not intend. Something they normally know how to do is suddenly difficult, then easy again later. Dell included imposed thoughts, emotions, impulses, actions, internal voices, and changes in skill among the dissociative intrusions reported in DID.²

Sometimes the clue is ordinary. A delivery appears that the person does not remember ordering. A friend continues a conversation they cannot place. They recognize the words in a note as their own and still cannot remember writing it. An assessor will ask how often this happens, what was going on around it, and whether the gaps come with changes in identity or control.¹³

For some people, the first noticeable sign is time they cannot account for. Other gaps are smaller: the outline of an event remains, but important details are gone; something is known to have happened without feeling fully lived. A change in mood or surroundings can sometimes bring more of the memory back.⁴

Dissociation can also make the body or the room feel unfamiliar. A person may feel outside their body, fail to recognize their reflection for a moment, or watch an action unfold without feeling that they began it. Familiar surroundings can look flat, distant, or unreal. The SCID-D asks about depersonalization and derealization alongside amnesia and identity alteration.³²

Some people hear internal voices or feel an emotion arrive without a story attached to it. The experience can be frightening long before it is recognized as dissociation.²

What clinicians are looking for

Diagnosis starts with the pattern across time: changes in identity and agency, memory gaps beyond ordinary forgetting, and disruption to daily life. An assessor also asks what else could account for it.¹⁵⁶

ICD-11 spells out one point that is easy to miss when DID is imagined as a complete blackout after every switch: a change in identity state does not need to bring amnesia every time. Substantial episodes of amnesia are still usually present at some point. DSM-5-TR makes clear that identity disruption can be reported by the person or observed by somebody else.⁶⁵

ICD-11

ICD-11 lists DID under 6B64. Its requirements are:⁶

Two or more distinct identity states, with marked breaks in the person's sense of self and agency.
At least two states repeatedly taking control of consciousness and daily functioning. This may happen during ordinary parts of life, such as work or parenting, or only in particular situations.
A change in state accompanied by related changes in sensation, perception, emotion, thinking, memory, movement, or behaviour.
Episodes of amnesia that go beyond ordinary forgetting. Amnesia does not have to occur with every change in state, though substantial episodes are usually present at some point.
Symptoms that interfere with personal, family, social, educational, or working life. Someone who keeps those areas going through significant extra effort can still meet this requirement.
Other explanations being ruled out, including another mental disorder, a substance or medication, neurological disease, or a sleep-wake disorder.
DID is not assigned when multiple states are part of a culturally accepted practice, do not feel unwanted, and do not interfere with daily life.

DSM-5-TR

DSM-5-TR sets out five criteria:⁵

A disruption of identity involving two or more distinct personality states, which may be described in some cultures as possession. The change includes a break in the person's sense of self and agency, with related changes in emotion, behaviour, awareness, memory, perception, thinking, or movement. It can be reported by the person or observed by someone else.
Recurring gaps in memory for everyday events, important personal information, or traumatic events. The gaps go beyond ordinary forgetting.
The symptoms cause significant distress or interfere with social life, work, or another important area.
The experience is not an ordinary part of a broadly accepted cultural or religious practice. In children, it is not better explained by imaginary playmates or fantasy play.
The symptoms are not caused by a substance or another medical condition, such as certain kinds of seizure.

Why the name changed

Clinicians described dissociation and divided identity long before modern diagnostic manuals.⁷ DSM-III called the diagnosis multiple personality disorder. DSM-IV later introduced the name dissociative identity disorder. “Multiple personality” suggests that several people or personalities inhabit the same body. The newer name describes disruptions within one person's identity and memory.⁸ For the longer story, read How our understanding of trauma and dissociation changed.

Parts and identity states

People use several words for the self-states involved in DID: parts, alters, identity states.⁹ The exact term matters less than whether it helps the person describe and understand the experience.

You may be easygoing with an old friend and guarded at work, yet both ways of being still feel like you. Therapists may call these ego states. A person generally carries the same memories and personal history between them.¹⁰

An action, message, or memory may seem to belong to someone else, alongside changes in control or access to memory.¹⁰ Clinical guidance treats every identity state as part of one person, even when the states feel separate.⁹

A child-identified state may feel very young and deserves patience and respect. Treating that state as a literal child, separate from the adult person, can create problems in therapy.¹¹ Therapy needs to support the adult person's life outside the session.⁹

Internal Family Systems (IFS) also uses “parts,” but it begins from the idea that every mind contains subpersonalities. An IFS part is not another name for a dissociative identity state. The IFS and dissociative parts page explains why a therapist may need to work with them differently.¹²¹⁰

What improvement can look like

Improvement does not require identity states to disappear completely.¹³ Some may opt for final fusion, some may not. You may notice fewer dangerous gaps, steadier days, more shared awareness, or less time spent in crisis. A week that used to collapse into crisis may become a week you can mostly account for.

In long-term follow-up studies, many people receiving specialist care improved in symptoms and daily functioning, with fewer hospitalizations and less self-harm. Read Better is not the same as finished for more on the six-year follow-up.¹⁴

International Society for the Study of Trauma and Dissociation. (2011). Guidelines for treating dissociative identity disorder in adults, third revision. Journal of Trauma & Dissociation, 12(2), 115-187. pp. 117-118. Core diagnostic features, including identity disruption and amnesia. ↩ ↩² ↩³
Dell, P. F. (2006). A new model of dissociative identity disorder. Psychiatric Clinics of North America, 29(1), 1-26. Box 1; pp. 9-10; proposed subjective/phenomenological model. Dell's proposed three-part framework: general dissociative symptoms, partially dissociated intrusions, and fully dissociated intrusions marked by amnesia; the paper distinguishes this proposal from current diagnostic criteria. ↩ ↩² ↩³
Steinberg, M. (2023). The SCID-D interview: Dissociation assessment in therapy, forensics, and research. American Psychiatric Association Publishing. Description and contents; Five Component Model. Purpose, symptom domains, structure, classification mapping, and administration requirements for the SCID-D. ↩ ↩²
Huntjens, R. J. C., Verschuere, B., & McNally, R. J. (2012). Inter-identity amnesia in dissociative identity disorder: A simulated memory impairment? PLOS ONE, 7(7), e40580. Results and discussion. Difference between subjective amnesia reports and performance on experimental memory tasks. ↩
American Psychiatric Association. (2022). Diagnostic and statistical manual of mental disorders (5th ed., text rev.). pp. 330-331, Dissociative identity disorder. DSM-5-TR diagnostic criteria for dissociative identity disorder, including identity disruption, recurrent memory gaps, impairment, and exclusions. ↩ ↩² ↩³
World Health Organization. (2024). Clinical descriptions and diagnostic requirements for ICD-11 mental, behavioural and neurodevelopmental disorders. pp. 382-383, Essential (required) features and Additional clinical features. ICD-11 DID requirements, including recurrent executive control by at least two identity states, amnesia, impairment, exclusions, and the normality threshold. ↩ ↩² ↩³
van der Hart, O., & Horst, R. (1989). The dissociation theory of Pierre Janet. Journal of Traumatic Stress, 2(4), 397-412. Abstract. Historical account of Janet's theory of dissociation as a response to overwhelming experience and of his concepts of memory, emotion, and psychological integration. ↩
Young, M., Almaskati, M., Vrabtchev, S., & Kuruvilla, T. (2024). Dissociative identity disorder: A review of the diagnosis that divides. Progress in Neurology and Psychiatry, 28(2), 23-27. Diagnostic history and current DSM/ICD descriptions. Clinical review of DID's diagnostic history, classifications, controversies, and current clinical implications. ↩
International Society for the Study of Trauma and Dissociation. (2011). Guidelines for treating dissociative identity disorder in adults, third revision. Journal of Trauma & Dissociation, 12(2), 115-187. pp. 120-121. Clinical language for identity states and the person as a whole. ↩ ↩² ↩³
Mosquera, D. (2023, July 1). What are dissociative parts and how or when to introduce 'parts' language? European Society for Trauma and Dissociation. Sections: What are dissociative parts?; How to distinguish dissociative parts from ego states?. Clinical distinctions between ego states and dissociative parts, including boundaries, autobiography, autonomy, and first-person perspective. ↩ ↩² ↩³
Shusta-Hochberg, S. R. (2004). Therapeutic hazards of treating child alters as real children in dissociative identity disorder. Journal of Trauma & Dissociation, 5(1), 13-27. pp. 13-27; abstract and clinical discussion. Clinical discussion of the risks of treating child-identified states as literal children. ↩
IFS Institute. (n.d.). The Internal Family Systems model outline. Sections I and III: Basic assumptions; Parts. The IFS model treats parts as subpersonalities within a naturally multiple mind and describes how they may be experienced. ↩
International Society for the Study of Trauma and Dissociation. (2011). Guidelines for treating dissociative identity disorder in adults, third revision. Journal of Trauma & Dissociation, 12(2), 115-187. pp. 132-134. Treatment goals, coordinated functioning, and integration. ↩
Myrick, A. C., Webermann, A. R., Loewenstein, R. J., Lanius, R., Putnam, F. W., & Brand, B. L. (2017). Six-year follow-up of the treatment of patients with dissociative disorders study. European Journal of Psychotraumatology, 8(1), 1344080. Results, limitations, and conclusions. Naturalistic symptom and functioning outcomes over six years. ↩