Dissociative disorders (DD) are conditions that involve disruptions or breakdowns of memory, awareness, identity, or perception. People with dissociative disorders use dissociation as a defense mechanism, pathologically and involuntarily. The individual experiences these dissociations to protect themselves. Some dissociative disorders are triggered by psychological trauma, but depersonalization-derealization disorder may be preceded only by stress, psychoactive substances, or no identifiable trigger at all. The dissociative disorders listed in the American Psychiatric Association's DSM-5 are as follows: Dissociative identity disorder (formerly multiple personality disorder): the alternation of two or more distinct personality states with impaired recall among personality states. In extreme cases, the host personality is unaware of the other, alternating personalities; however, the alternate personalities can be aware of all the existing personalities. Dissociative amnesia (formerly psychogenic amnesia): the temporary loss of recall memory, specifically episodic memory, due to a traumatic or stressful event. It is considered the most common dissociative disorder amongst those documented. This disorder can occur abruptly or gradually and may last minutes to years depending on the severity of the trauma and the patient. Dissociative fugue was previously a separate category but is now treated as a specifier for dissociative amnesia. Depersonalization-derealization disorder: periods of detachment from self or surrounding which may be experienced as "unreal" (lacking in control of or "outside" self) while retaining awareness that this is only a feeling and not a reality. The old category of dissociative disorder not otherwise specified is now split into two: other specified dissociative disorder, and unspecified dissociative disorder. These categories are used for forms of pathological dissociation that do not fully meet the criteria of the other specified dissociative disorders; or if the correct category has not been determined; or the disorder is transient. The ICD-11 lists dissociative disorders as: Dissociative neurological symptom disorder Dissociative amnesia Dissociative amnesia with dissociative fugue Trance disorder Possession trance disorder Dissociative identity disorder Partial dissociative identity disorder Depersonalization-derealization disorder Cause and treatment Dissociative identity disorder Cause: Dissociative identity disorder is caused by ongoing childhood trauma that occurs before the ages of six to nine. People with dissociative identity disorder usually have close relatives who have also had similar experiences. Treatment: Long-term psychotherapy to improve the patient's quality of life. Dissociative amnesia Cause: A way to cope with trauma. Treatment: Psychotherapy (e.g. talk therapy) counseling or psychosocial therapy which involves talking about your disorder and related issues with a mental health provider.