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Ganser's syndrome


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Professional Reference articles are designed for health professionals to use. They are written by UK doctors and based on research evidence, UK and European Guidelines. You may find one of our health articles more useful.

Synonyms: prison psychosis, pseudodementia, hysterical pseudodementia

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What is Ganser's syndrome?

This is a rare condition of uncertain or variable aetiology. It was first described by the psychiatrist Sigbert Ganser in 1898. Ganser described the syndrome after studying the behaviour of three inmates of a prison and thus it has acquired the synonym 'prison psychosis'. He was of the opinion that the condition was hysterical or malingering in origin.

Ganser's syndrome causes (aetiology)

It is thought that people develop Ganser's syndrome, either consciously or unconsciously, to avoid an unpleasant situation. There has been much debate over the years as to whether it is psychotic, dissociative, or factitious in origin. Association with serious illness may suggest an aetiology similar to delirium. It is fairly common to find it associated with head injury. There may be no one cause in all cases.

The International Classification of Diseases (ICD-11) classifies Ganser's syndrome as a dissociative disorder.1 It has often been classified instead as a factitious disorder; for example, it was classed as such in the 3rd edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III), and reclassified to a dissociative disorder in DSM-IV. It is not currently in the DSM-5.2

Whilst some believe the syndrome actually represents deliberate simulation and malingering, Ganser himself was less convinced of this explanation; in the original three patients he described, he took care to note that two had just experienced head injuries, and the third, a severe case of typhus fever.3

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How common is Ganser's syndrome? (Epidemiology)

Ganser's syndrome is said to be very rare, with its exact incidence unknown.3 One review found only 117 cases had been reported in the Dutch, English, German and French language literatures between 1898 and 2016.4 Most of the recorded cases in the literature describe only individual patients and criteria are lax. Ganser's syndrome is more common in men, with a probable male-to-female ratio of 3 or 4:1. It is most frequently described in individuals between the ages of 15 and 40 but a wide range of ages has been reported. It has been described in children.5 Ganser's syndrome is thought to be precipitated by episodes of severe stress but has also been described in association with head injury.

Ganser's syndrome symptoms3

The condition tends to occur against a background of head injury or serious illness. Severe psychosocial stress can also be a cause; psychosocial stresses accompanying immigration may have a catalytic effect in triggering the condition.6 The four principal features are:

  • Approximate answers.

  • Clouding of consciousness.

  • Somatic conversion symptoms such as hysterical paralysis.

  • Hallucinations, visual or auditory.

The term approximate answers needs explanation. It is the most characteristic feature of the condition and German terms such as vorbeireden meaning talking past and vorbeigehen meaning to pass by or danebenreden meaning talking next to are used in the literature. The essential feature of approximate answers is that whilst the patient gives an incorrect response, the nature of the response suggests that he/she understands the question. Thus, the patient may say that grass is blue and that a dog has three legs. When asked the day of the week or month of the year, he/she will give a day of the week or month of the year but the wrong one. This is in direct contrast to answers that are simply nonsensical, perseverative or otherwise inappropriate.

Diagnostic criteria are not well established. Most authorities would want approximate answers and at least one other principal feature to make the diagnosis.

A key distinguishing feature from other psychiatric conditions is that symptoms of Ganser's syndrome recover spontaneously, without any specific treatment.3

Other features include:

  • A dreamy or perplexed appearance.

  • Memory or personal identity loss.

  • No recollection of the condition upon recovery.

  • Perseveration.

  • Echolalia.

  • Echopraxia.

  • Confusion.

  • Precipitating stress.

  • Loss of personal identity.

There is no typical finding on examination. A full neurological examination should be performed and a mental state examination. There are now more sophisticated tests to assess exaggerated or fabricated cognitive dysfunction.7 Look for signs of self-inflicted injury.

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Differential diagnosis3

Associated diseases3

Ganser's syndrome has been reported in the following:

  • Neurosyphilis

  • Epilepsy

  • Post-stroke

  • Meningiomas

  • Post-anoxia

  • Postpartum psychosis

  • Traumatic brain injuries

  • Infections

  • Various dementias


No investigation is diagnostic but a number may be performed to exclude other pathology. It is important to exclude an underlying organic cause.

  • Mental state examination should be performed.

  • FBC.

  • U&Es.

  • LFTs.

  • Vitamin B12 levels.

  • TFTs.

  • Urine drug screen

  • CT scan or MRI scan to exclude structural pathology.

  • Lumbar puncture may be performed to exclude meningitis or encephalitis.

  • Electroencephalograph (EEG) does not usually show any specific disorder.8 However, it should be performed to rule out underlying causes such as delirium or seizure disorder.

One study reported that a man pursuing an insurance claim presented with Ganser's syndrome-like symptoms. Simple memory tests and the existence of symptoms not typical of the syndrome were used to exclude the syndrome.9

Ganser's syndrome treatment and management3

Admission to a psychiatric unit in the acute phase may be required for assessment and to prevent harm to self or to others. Simple psychotherapy is the mainstay of treatment. Drug therapy is of limited value and not usually required. Evidence of benefit from benzodiazepines, antipsychotic medication or other treatments, such as electroconvulsive therapy or hypnosis, is very limited.


If the precipitating stress has been withdrawn, symptoms usually resolve spontaneously within days but there is usually no recollection of the illness. Sometimes severe depression follows.

Mortality and morbidity are related to the underlying cause, especially if organic.

Further reading and references

  1. International Classification of Diseases 11th Revision; World Health Organization, 2019/2021
  2. Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR) - 5th ed; text rev; American Psychiatric Association American Psychiatric Association, 2022
  3. Dwyer J, Reid S; Ganser's syndrome. Lancet. 2004 Jul 31-Aug 6;364(9432):471-3.
  4. A systematic report review of Ganser syndrome: 118 years of case studies; Cambridge University Press, March 2020, Copyright © European Psychiatric Association 2017
  5. Spodenkiewicz M, Taieb O, Speranza M, et al; Case report of Ganser syndrome in a 14-year-old girl: another face of depressive disorder? Child Adolesc Psychiatry Ment Health. 2012 Feb 1;6(1):6. doi: 10.1186/1753-2000-6-6.
  6. Staniloiu A, Bender A, Smolewska K, et al; Ganser syndrome with work-related onset in a patient with a background of immigration. Cogn Neuropsychiatry. 2009 May;14(3):180-98.
  7. Wisdom NM, Callahan JL, Shaw TG; Diagnostic utility of the structured inventory of malingered symptomatology to detect malingering in a forensic sample. Arch Clin Neuropsychol. 2010 Mar;25(2):118-25. Epub 2010 Jan 28.
  8. Boutros NN, Struve F; Electrophysiological assessment of neuropsychiatric disorders. Semin Clin Neuropsychiatry. 2002 Jan;7(1):30-41.
  9. Merckelbach H, Peters M, Jelicic M, et al; Detecting malingering of Ganser-like symptoms with tests: a case study. Psychiatry Clin Neurosci. 2006 Oct;60(5):636-8.

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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