A 24-year-old man is brought into an A&E department by the Police. He has been found wandering the streets locally. He is unable to remember anything from his past and is unsure where he is. He is also unable to answer questions about his own personal identity. His physical examination is unremarkable and there are no signs of drug use or intoxication.

1. What is the most likely diagnosis?

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This patient is suffering from dissociative fugue, which is also known as a fugue state. This is a relatively rare transient psychiatric disorder characterised by amnesia of personal identity, past events and personality traits. Patients sometimes assume completely new identities and often undergo unplanned travel away from familiar surroundings. Dissociative fugue is usually short lived but in rare cases it can last for several weeks enabling patients to adopt completely new identities. The condition often resolves abruptly and patients can experience post fugue depression, shame and anger. 

2. What is the cause of this condition?

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The exact cause of dissociative fugue is not fully understood but it has been linked to traumatic or stressful life events such as abuse, accident or extreme violence. Other factors that are though to predispose to the development of dissociative fugue include neuropsychological cognitive dysfunctions and genetic factors.

3. Which other factors or conditions should be excluded?

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There are many factors and conditions that can cause similar effects to dissociative fugue and it is important that a differentiation is made between a dissociative fugue episode and dissociative fugue-like symptoms caused by a drug, medical condition or psychological disorder.

Factors and conditions that can cause dissociative fugue-like symptoms include:

  • Alcohol abuse
  • Use of hallucinogens and cannabis
  • Head trauma
  • Brain tumours
  • Schizophrenia
  • Mania

4. How is this condition treated?

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The mainstay of treatment of dissociative fugue is psychotherapy. Attempts should be made to elicit any stressors that preceded the development of the disorder. The patient and their family should be educated about the disorder and efforts made to reduce any stressors that may precipitate another episode.

If the patient is still in a fugue state, the first concern is to ensure the safety and wellbeing of the patient. As dissociative fugue is often co-morbid with psychiatric disorders, drug treatments may be necessary for the latter.

5. What is transient global amnesia? 

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Transient global amnesia (TGA) also presents with transient memory loss but in contrast to fugue state there is preservation of the patient’s identity and personality. TGA typically presents in patients over the age of 50 with an almost total disruption of short-term memory. They often repeatedly ask pertinent questions and it can occur following strenuous exercise, sexual intercourse and exposure to cold temperatures.