Introduction

Dissociative disorder not otherwise specified (DDNOS) is a mental health diagnosis for pathological dissociation that matches the DSM-5 criteria for a dissociative disorder, but does not fit the full criteria for any of the specifically identified subtypes, which include dissociative identity disorder, dissociative amnesia, and depersonalisation/derealisation disorder, and the reasons why the previous diagnoses were not met are specified.

Refer to Depressive Disorder Not Otherwise Specified (DD-NOS).

Background

“Unspecified dissociative disorder” is given when the clinician does not give a reason. The International Statistical Classification of Diseases and Related Health Problems (ICD-10) refers to the diagnosis as “Other dissociative and conversion disorders”.

Examples of DDNOS include chronic and recurrent syndromes of mixed dissociative symptoms, identity disturbance due to prolonged and intense coercive persuasion, disorders similar to dissociative identity disorder, acute dissociative reactions to stressful events, and dissociative trance.

DDNOS is the most common dissociative disorder and is diagnosed in 40% of dissociative disorder cases. It is often co-morbid with other mental illnesses such as complex posttraumatic stress disorder, major depressive disorder, generalised anxiety disorder, personality disorders, substance use disorders, and eating disorders.