Dissociative identity disorder: symptoms, causes and treatment

Key points

• Dissociative identity disorder (DID) is a condition in which identity is divided between two or more distinct personality states, with gaps in memory ordinary forgetting does not explain [2].
• It was previously called multiple personality disorder, a name no longer used clinically [1][9].
• Amnesia between states is the diagnostic core, and the part films and television usually leave out [2].
• How DID develops is disputed among researchers, though the experiences people report are not [6].
• People with DID are far more likely to be harmed, including by themselves, than to harm anyone [3][10].
• There is no NICE guideline for DID and almost no specialist NHS provision [3][8].

What dissociative identity disorder is

Dissociative identity disorder (DID) is a mental health condition in which a person’s sense of identity is split between two or more distinct personality states, each with its own way of thinking, remembering and relating to the world [2]. The person also has recurring gaps in memory for everyday events and personal information that ordinary forgetting does not explain [2].

If you need help now. Samaritans: call 116 123, free, 24/7. Shout: text SHOUT to 85258. NHS 111, then choose the mental health option. Call 999 if anyone is in immediate danger.

DID was known for many years as multiple personality disorder [1]. Researchers now describe it as one identity that has not held together rather than several complete personalities [8].

No UK prevalence study has been published [3]. Estimates from elsewhere put it at around 1.5% of the general population [4].

Symptoms

Identity:

• Two or more distinct personality states, often called “alters” or “parts”, together a “system” [7].
• Changes in voice, posture, mannerisms or apparent age when another state takes over [8].
• A sense of being influenced or spoken to from inside one’s own mind, or detached from one’s own body [1][3].

Memory:

• Gaps in recall for ordinary daily events, not only for trauma, lasting from minutes to days [1][2].
• Finding objects, messages or purchases with no memory of them [7].

Associated difficulties:

• Flashbacks, nightmares and other post-traumatic symptoms [3].
• Depression, anxiety, self-harm and suicidal thoughts [9].

DID is commonly confused with psychosis, because hearing voices is frequent, with bipolar disorder, because switching can look like rapid mood change, and with borderline personality disorder, with which it overlaps heavily: rates of comorbid dissociative disorder in people with borderline personality disorder have been reported as high as 75% [3].

Types

ICD-11, the World Health Organization’s current classification, lists two related diagnoses rather than subtypes of one condition [2].

• Dissociative identity disorder (6B64). Two or more personality states recurrently take control of behaviour, with gaps in memory beyond ordinary forgetting [2].
• Partial dissociative identity disorder (6B65). One state stays dominant and runs daily life, while other states intrude on thoughts, emotions or perception without repeatedly taking control [2].

Both sit within the wider group of dissociative disorders, alongside dissociative amnesia and depersonalisation-derealisation disorder [1]. Neither ICD-11 nor DSM-5-TR sets severity bands for DID [2][9].

Causes and risk factors

No single agreed explanation exists for how DID develops. A BJPsych Advances editorial noted that the science looks convincing to people on each side, and that a shortage of primary research keeps the argument open [6].

The trauma model holds that repeated, severe trauma in early childhood, before identity has settled, leads a child to keep experience separated as a way of coping that persists into adult life [1][7]. About 90% of people diagnosed with DID in North America and Europe report childhood abuse and neglect [9]. Imaging studies report activity patterns that differ from those of people asked to simulate the condition [4].

The sociocognitive or iatrogenic model holds that DID is shaped by expectation, suggestion, therapist belief and cultural portrayals, and that it is over-diagnosed in some settings [5]. Its supporters note that dissociative symptoms are easy to fabricate and that most of the literature is individual case reports [5].

Not in dispute is that the experiences themselves, the lost time, identity confusion and distress, are real and disabling whatever their origin [3][6]. Recognised risk factors include childhood abuse or neglect [9], other severe early adversity [1], and other post-traumatic conditions [3].

How it is diagnosed

In the UK, DID is diagnosed by a psychiatrist or clinical psychologist in secondary mental health services, usually after a GP referral [1]. GPs do not make the diagnosis themselves and often have limited familiarity with dissociative disorders [8].

Assessment involves a long clinical interview covering memory gaps, identity states and trauma history, supported by the Dissociative Experiences Scale (DES-II) for screening and the Structured Clinical Interview for Dissociative Disorders (SCID-D-R), the closest thing to a diagnostic standard [3].

Diagnosis is usually slow. The average time to diagnosis is often quoted at around seven years, and for many it is considerably longer [3]. People commonly receive around four other diagnoses first [4].

A diagnosis indicates a pattern of dissociative symptoms. It does not mean a person is dangerous or unable to work [10], and it does not establish that memories described in therapy are accurate [5].

Treatment

No NICE guideline covers DID, so UK treatment follows general trauma and dissociation practice rather than a national standard [3]. The NHS lists talking therapies such as counselling and psychotherapy, eye movement desensitisation and reprocessing (EMDR), and medication for co-occurring depression or anxiety rather than for DID itself [1][8].

The most widely used approach is phase-based, and specialist accounts describe it running over several years [3]:

• Safety and stabilisation. Reducing risk, managing dissociation and building coping skills.
• Processing traumatic memories. Trauma-focused work at a pace the person can manage.
• Integration and rehabilitation. Rebuilding functioning, relationships and daily life.

The evidence base is limited: no randomised controlled trials of treatment for DID exist, and the literature consists largely of case studies and small follow-up studies [5]. Specialist provision is scarce, and the Trauma and Dissociation Service at South London and Maudsley is described as the only NHS specialist service for severe dissociative disorders, so most people are seen by community mental health teams [8].

Living with dissociative identity disorder

Keeping a written record helps information carry across gaps in memory. A notebook, shared calendar or phone notes can hold appointments, decisions and what happened during time you cannot recall.

Recording what tends to precede switching or losing time gives a clinician something to work with. Grounding skills taught during stabilisation are the tools most people rely on day to day [3].

Agree a written crisis plan with the professional treating you. Rates of self-harm and attempted suicide are high in this group, and a plan made in advance is easier to follow [3][9].

At work or university you do not have to give a diagnosis. Many people describe the effects instead, such as difficulty holding information, and ask for written instructions. If an assessment leaves you dismissed, Mind suggests asking your doctor to refer you to someone who knows more about dissociation for a full assessment [7].

When to speak to a professional

Speak to your GP if you regularly lose time, cannot account for events other people describe, or find your sense of who you are shifting in ways you cannot control. Ask about referral to secondary mental health services, since dissociative disorders are assessed there rather than in NHS Talking Therapies for anxiety and depression [1].

Seek help the same day if you are self-harming, thinking about suicide, or unable to keep yourself safe. Call NHS 111 and choose the mental health option, or your local crisis team. Call 999 if anyone is in immediate danger. Samaritans is free on 116 123, and Shout takes texts: text SHOUT to 85258.

Common questions

Is dissociative identity disorder real?

DID is a recognised diagnosis in ICD-11, the World Health Organization’s current classification, and in DSM-5-TR [2][9]. Researchers argue about how it develops, not about whether people genuinely have the experiences they report, and both sides accept that the symptoms cause real distress [6].

Is DID the same as multiple personality disorder?

They are the same condition, and multiple personality disorder is the older term [1]. The name changed partly because the condition involves one identity that has not held together, rather than several complete personalities [8].

Are people with DID dangerous?

Portrayals linking DID to violence are inaccurate, and Mind describes them as a harmful stereotype [7]. People with severe mental illness are around five times more likely to be assaulted than the general population, and women around ten times more likely [10]. Risk in DID is mainly to the person themselves [3][9].

Can DID be treated?

Treatment aims to reduce dissociation, memory loss and distress and to improve daily functioning, usually through phase-based trauma work over a long period [3]. Some people work towards their identity states co-operating, others towards integration [3]. The evidence supporting any particular approach is limited, and outcomes vary [5].

Clinical review pending

References

1. NHS. Dissociative disorders. NHS, accessed August 2026. https://www.nhs.uk/mental-health/conditions/dissociative-disorders/
2. World Health Organization. Clinical descriptions and diagnostic requirements for ICD-11 mental, behavioural and neurodevelopmental disorders. WHO, 2024. https://www.drugsandalcohol.ie/41519/1/WHO_Clinical_descriptions_and_diagnostic_requirements_ICD-11.pdf
3. Temple MJ. Understanding, identifying and managing severe dissociative disorders in general psychiatric settings. BJPsych Advances, 2019;25(1):14-25. https://www.cambridge.org/core/journals/bjpsych-advances/article/understanding-identifying-and-managing-severe-dissociative-disorders-in-general-psychiatric-settings/62CC0133915C7F47CDAFADC230EE5001
4. Reinders AATS, Veltman DJ. Dissociative identity disorder: out of the shadows at last? The British Journal of Psychiatry, 2021;219(2):413-414. https://www.cambridge.org/core/journals/the-british-journal-of-psychiatry/article/dissociative-identity-disorder-out-of-the-shadows-at-last/8E2884FA8669A9A64790E5C47AD72DC7
5. Paris J. Dissociative identity disorder: validity and use in the criminal justice system. BJPsych Advances, 2019;25(5):287-293. https://www.cambridge.org/core/journals/bjpsych-advances/article/dissociative-identity-disorder-validity-and-use-in-the-criminal-justice-system/C1C27EE9731782570E1376A3EDA48CE4
6. Casey P. Editor’s comment: the debate on dissociative identity disorder. BJPsych Advances, 2021;27(2):102-103. https://www.cambridge.org/core/journals/bjpsych-advances/article/editors-comment-the-debate-on-dissociative-identity-disorder/E1384DFA8CC54DC3DF19AFBEB2CFA0F0
7. Mind. Dissociative disorders. Mind, accessed August 2026. https://www.mind.org.uk/information-support/types-of-mental-health-problems/dissociation-and-dissociative-disorders/dissociative-disorders/
8. Rethink Mental Illness. Dissociation and DID explained: what it is, causes and treatment. Rethink Mental Illness, accessed August 2026. https://www.rethink.org/advice-and-information/about-mental-illness/mental-health-conditions/dissociation-and-dissociative-identity-disorder-did/
9. American Psychiatric Association. What are dissociative disorders? APA, accessed August 2026. https://www.psychiatry.org/patients-families/dissociative-disorders/what-are-dissociative-disorders
10. Victim Support, Mind, Institute of Psychiatry and St George’s University of London. At risk, yet dismissed: the criminal victimisation of people with mental health problems. Victim Support, 2013. https://www.victimsupport.org.uk/wp-content/uploads/documents/files/At%20risk,%20yet%20dismissed%20-%20summary.pdf