Dissociative Disorders – What are they?

Aimee Aveyard
Author: Aimee Aveyard Medical Reviewer: Tayler Hackett Last updated:

Dissociative disorders are a group of mental illnesses characterized by disconnections between thoughts, feelings, memories, identity, the body, and the outside world. They include dissociative identity disorder, dissociative amnesia and depersonalization / derealization disorder.

Symptoms of dissociative disorders

Dissociative disorders involve involuntary breaks from reality.[1] Most of us experience some form of dissociation at times, such as daydreaming or being so lost in thought while driving home that we can’t remember the journey. If you have a dissociative disorder, breaks from reality will have a significant impact on your memories, identity, consciousness, your behavior, how you view yourself and how you feel about your external environment.[2]

The key dissociative symptoms include:

  • Amnesia, which is significant memory loss. It may concern particular periods of time or specific situations. Amnesia may extend to long periods of a person’s life and may even affect their ability to recall who they are.[2]
  • Depersonalization, which is a feeling of being detached from oneself, in which a person might feel numb, robotic,or as though they are observing themselves.[3]
  • Derealization, which is a feeling of detachment from the outside world, which may include a feeling that things around you are distorted and not real.[3]

Types of dissociative disorder

The three main types of dissociative disorder are dissociative identity disorder, dissociative amnesia and depersonalization / derealization disorder.

Dissociative identity disorder

Dissociative identity disorder (DID) is a medical condition in which a person experiences significant changes to their sense of personal identity. It used to be called ‘multiple personality disorder’.[4] The person develops two or more distinct personalities (known as ‘alters’) with different ways of behaving and viewing the world. Some people experience personalities of different ages or genders. Some people with DID have up to 100 alters.

The person switches between different alters and may experience gaps in memory as a result. They may find themselves in a place they don’t remember travelling to, see evidence of having done things they don’t remember doing or have a feeling of ‘coming to’ in the middle of a task.[2] 

The people around the person with dissociative identity disorder may witness significant changes in how a person speaks or behaves while in different personality states.[2]

In some cultures, dissociative identity disorder is viewed as possession, where it appears an external force or being has taken over a person’s body.[2] 

Many people with dissociative identity disorder also develop other mental health conditions, such as post-traumatic stress disorder (PTSD), depressive disorders, personality disorders, eating disorders, substance misuse, obsessive compulsive disorder (OCD) and sleep problems.[2] 

Dissociative amnesia

Dissociative amnesia is a condition in which a person is unable to recall memories about periods of their life. It may be that a specific traumatic experience has been forgotten or that a person has a more general lack of memory about their life or who they are.[2]

Dissociative amnesia is different from other types of amnesia that might be caused by brain damage or drug use. Dissociative amnesia is believed to be reversible – a suppression of memories – rather than the permanent memory loss that can occur when there is a physical, biological cause.[2] 

People with dissociative amnesia often have other mental health problems as well, including depression and personality disorders. Dissociative amnesia is commonly associated with post-traumatic stress disorder, particularly if suppressed traumatic memories resurface.[2] It can also be a consequence of post-traumatic stress disorder, in order to cope with painful memories.

Depersonalization / derealization disorder

Depersonalization / derealization disorder is the repeated experience of states of depersonalization or derealization.


Depersonalization is a sense of feeling detached from oneself.

It may include:[3]

  • Feeling robotic or like you are living ‘on autopilot’
  • Feeling as though you are observing yourself from the outside
  • Problems with thinking clearly or concentrating
  • Feeling emotionally numb
  • Feeling physically numb
  • Feeling that time is moving faster or slower than usual
  • A failure to recognize your own reflection or voice
  • A lack of certainty about your identity
  • Persistent questions about the meaning of life and the nature of existence 


Derealization is a sense of feeling detached from the outside world or from reality. 

It may include:[3]

  • A feeling that the world isn’t real
  • Experiencing surroundings as distorted – objects may seem larger or smaller than usual, sounds may seem strange, colors may seem muted
  • Familiar places feeling foreign
  • Feeling like you are in a dream 

People will often experience both together, while at the same time maintaining an awareness that these feelings are not real.[2]

Studies have shown that people with depersonalization / derealization disorder often also have depression and anxiety disorders, as well as a personality disorder. Post-traumatic stress disorder (PTSD) is a common factor in the development of depersonalization / derealization disorder.

Causes of dissociative disorders

Dissociative disorders are believed to develop after trauma or significant stress, often as a result of childhood abuse. Dissociation has been likened to a kind of mental safety mechanism, protecting the self from pain or fear that is too overwhelming to cope with.[5] Dissociative disorders can also develop in adulthood, after a traumatic event such as a sexual assault, in order to mentally disconnect from one’s body.

How are dissociative disorders diagnosed?

As dissociative disorders are complex, diagnosis is made by a specialist mental health professional following a psychological evaluation. This evaluation includes the discussion of signs and symptoms, a review of medical history and sometimes questionnaires. It is important to rule out drugs and other medical problems including other mental health problems as possible causes before a diagnosis is made, which may involve carrying out medical tests.[2]

How are dissociative disorders treated?

Treatment for dissociative disorders usually focusses on psychotherapy.

These include: 

  • Cognitive behavioral therapy (CBT) and dialectical behavioral therapy (DBT) which can help with managing difficult emotions and learning new ways to cope.[5]
  • Eye-movement desensitization and reprocessing (EMDR) which is a therapy that can help with the processing of traumatic memories. EMDR needs to be adapted and used carefully in people with dissociative disorders.[4]
  • Hypnotherapy, which can be used to treat dissociative identity disorder.[5]

Medication is not used specifically for dissociative disorders but can be used to treat associated symptoms or co-existing mental health problems, such as antidepressants for depressive symptoms.[5]

  1. Dissociative Disorders. (n.d.). National Alliance of Mental Illness. Arlington, VA. Retrieved November 27, 2022, from https://www.nami.org/About-Mental-Illness/Mental-Health-Conditions/Dissociative-Disorders
  2. American Psychiatric Association. (2013, May 27). Diagnostic and Statistical Manual of Mental Disorders, 5th Edition: DSM-5(5th ed.). American Psychiatric Publishing. Retrieved November 27, 2022, from https://psychiatry.org/psychiatrists/practice/dsm
  3. Hunter, Elaine et al. (2018). Overcoming Depersonalization and Feelings of Unreality, 2nd Robinson. London, United Kingdom.
  4. Dissociation and dissociative disorders. (2019, March). Mind. London, United Kingdom. Retrieved November 27, 2022, from https://www.mind.org.uk/information-support/types-of-mental-health-problems/dissociation-and-dissociative-disorders/dissociative-disorders
  5. What Are Dissociative Disorders? (2022, October). American Psychiatric Association. Washington, DC. Retrieved November 27, 2022, from https://www.psychiatry.org/patients-families/dissociative-disorders/what-are-dissociative-disorders
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Aimee Aveyard
Author Aimee Aveyard Writer

Aimee Aveyard is a medical writer with 20+ years of experience in communications.

Published: Dec 21st 2022, Last edited: Jan 12th 2024

Tayler Hackett
Medical Reviewer Tayler Hackett BSc, PGCert

Talyer Hackett is a medical writer and researcher with 10+ years of experience, holding B.A. in Psychology from the University of Liverpool.

Content reviewed by a medical professional. Last reviewed: Dec 21st 2022
Medical Reviewer Medical Reviewer:
Tayler Hackett
Last reviewed: Dec 21st 2022 Tayler Hackett

BSc, PGCert