Although dissociative disorders are typically an adaptive response to severe and protracted developmental trauma, they are classified as mental health disorders. This is because they usually cause great distress and significantly impaired capacity to function in at least one important area of life. At worst, they can cause extreme suffering and have a devastating impact on the person’s capacity to function overall.

At CDS UK, we work with all named dissociative disorders, including Dissociative Amnesia, Depersonalisation/Derealisation Disorder, Other Specified Dissociative Disorder (OSDD) and Dissociative Identity Disorder (DID).
The impact of complex trauma and dissociation can also sometimes manifest primarily in the body. This can be referred to as somatoform dissociation, conversion symptoms/disorder or medically unexplained symptoms (MUS). Many people with dissociative disorders also have multiple post-traumatic intrusions, such as flashbacks and nightmares.

We are aware that some survivors of trauma find the concept of diagnosis unhelpful or pathologising but include information about different diagnoses and types of dissociative experiences below.

The different dissociative disorders are categorised as follows:

Under the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, edition 5 (DSM-V), the symptoms and criteria for Dissociative Amnesia are:

  • An inability to recall important autobiographic information, usually of a traumatic or stressful nature, that is inconsistent with ordinary forgetting.
  • The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.
  • The disturbance is not attributable to the physiological effects of a substance or a neurological or other medical condition.
  • •he disturbance is not better explained by dissociative identity disorder, posttraumatic stress disorder, acute stress disorder, somatic symptom disorder, or major or mild neurocognitive disorder.

Dissociative Fugue is defined as a sub-type of Dissociative Amnesia under DSM-V. A fugue state occurs when there is sudden and unexpected travel away from home or work, in combination with amnesia for the past, and either identity confusion or the assumption of a new identity.

This is characterised by clinically significant persistent or recurrent feelings of depersonalisation, derealisation or both as predominant symptoms.

Depersonalisation is the feeling of being detached or disconnected from one’s body and/or mental and emotional processes. People often describe feeling unreal or numb, like an outside observer of their own life or having “out of body” experiences. They may even feel that they don’t have a body, whilst logically knowing that they do.

Derealisation includes feelings of unreality or detachment from the environment and/or people in it, sometimes described as “living in a fog” or “being behind a screen”. There may be an inability to recognise places and people that should be familiar and sensory distortions, such as a narrowed visual field, seeing things as smaller or bigger than they actually are, or sounds feeling either heightened or muted. Hypersensitivity to sensory stimuli is common in people with severe trauma.

This diagnosis applies to presentations in which dissociative symptoms cause clinically significant distress or impairment in important areas of functioning but do not meet the full criteria for any of the other dissociative disorders. Example presentations include the following:

  • Chronic and recurrent syndromes of mixed dissociative symptoms.
  • Identity disturbance due to prolonged and intense coercive persuasion.
  • Acute dissociative reactions to stressful events.
  • Dissociative trance.

The DSM-V specifies the following criteria for D.I.D

  • The presence of two or more distinct identities or personality states, each with its own relatively enduring pattern of perceiving, relating to, and thinking about the environment and self.
  • The occurrence of amnesia, defined as gaps in the recall of everyday events, important personal information and/or traumatic events.
  • The person must be distressed by the disorder or have trouble functioning in one or more major life areas because of it.
  • The disturbance is not part of normal cultural or religious practices.
  • The symptoms are not due to the direct physiological effects of a substance or a general medical condition.

People with severe trauma histories can sometimes experience multiple medically unexplained physical problems and disturbances in perception, sensation and control. These may include episodes of paralysis, temporary loss of sight or hearing, medically unexplained seizures, chronic pain syndromes and severe headaches with no clear medical explanation.

These can come and go and sometimes be associated with specific identities only, leading to disbelief and confusion in professionals. However, these experiences are very real to the person who experiences them and are not within their control.


Although we work with all dissociative disorders, the majority of people seen at CDS UK present with Dissociative Identity Disorder (DID). Research suggests that DID typically follows the experience of chronic and extreme early childhood trauma, along with the absence of a safe attachment figure, ie the absence of appropriate comfort or care (McQueen, D; Kennedy, R; Itzin, C; Sinason, V; Maxted, F, 2009).

There are many myths about DID as it is a complex, often poorly understood condition with many hidden symptoms. However, contemporary international research suggests that it is present in around 1.5% of the general population, though largely undiagnosed (ref ISSTD).

As with all trauma and mental health disorders, people with DID present with a vast spectrum of experience. It is not uncommon for people with DID to function well in certain areas of life and struggle greatly with others. Additionally, they can present in very different ways at different times depending on which identity or part is at the fore, which can be confusing for professionals if structural dissociation of the personality has not been identified or understood.

Typically, there is amnesia between different identities (also described as parts, alters, personalities). However, there may be awareness between identities (often referred to as co-consciousness), meaning that they can hear and potentially communicate with each other internally. Co-consciousness between identities also typically increases over the course of psychotherapy, leading to an improved quality of life and functioning. Particular situations or events may trigger flashbacks or bring certain identities to the fore.

People with DID may also meet the criteria for other diagnoses and many have received multiple diagnoses over the years. Those working within the field find that identifying structural dissociation of the personality through a primary DID diagnosis is fundamental in offering help that is clinically meaningful to the whole person and is likely to improve quality of life. A specialist assessment can be the best way for DID to be formally identified.

International research has shown that long-term specialist therapy is the most effective treatment option and that, as with all work with extreme and chronic trauma, short-term interventions are unlikely to have a lasting effect if used in isolation.

Major research from the Albert Einstein College of Medicine (Foote, Smolin, Neft and Lipschitz, 2008) has shown that adults with dissociative disorders are at high risk of suicide or self-harm, as well as sectioning and other unplanned psychiatric admissions. As a result of its clinical and theoretical understanding of this subject the risk of suicide or involuntary psychiatric admissions of CDS UK’s patients has been substantially reduced.

If you would like to read more about the origins and neurobiology of DID, please click here.