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Capgras delusion
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The Capgras delusion or Capgras' syndrome is a rare disorder in which a person holds a delusional belief that an acquaintance, usually a close family member or spouse, has been replaced by an identical looking impostor. Capgras delusion is classed as a delusional misidentification syndrome, a class of delusional beliefs that involves the misidentification of people, places or objects. It can occur in acute, transient, or chronic forms.
The delusion is most common in patients diagnosed with schizophrenia, although it can occur in a number of conditions including after brain injury and dementia.[1] Although Capgras is commonly called a syndrome, because it can occur as part of, or alongside, various other disorders and conditions some researchers have argued that it should be considered as a symptom, rather than a syndrome or classification in its own right.
Contents
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* 1 History
* 2 Presentation
* 3 Causes
* 4 In fiction
* 5 See also
* 6 References
[edit] History
It is named after Joseph Capgras (1873-1950), a French psychiatrist who first described the disorder in a 1923 paper by Capgras and Reboul-Lachaux.[2][3] They used the term l'illusion des sosies (the illusion of doubles) to describe the case of a French woman who complained that various "doubles" had taken the place of people she knew. However, the term illusion has a subtly different meaning from delusion in psychiatry so "Capgras delusion" is used as a more suitable name.
[edit] Presentation
This case is taken from a 1991 report by Passer and Warnock[4]:
Mrs. D, a 74-year old married housewife, recently discharged from a local hospital after her first psychiatric admission, presented to our facility for a second opinion. At the time of her admission earlier in the year, she had received the diagnosis of atypical psychosis because of her belief that her husband had been replaced by another unrelated man. She refused to sleep with the imposter, locked her bedroom and door at night, asked her son for a gun, and finally fought with the police when attempts were made to hospitalize her. At times she believed her husband was her long deceased father. She easily recognized other family members and would misidentify her husband only.
[edit] Causes
Some of the first clues to the possible causes of Capgras delusion were suggested by the study of brain injured patients who had developed prosopagnosia. In this condition, patients are unable to consciously recognise faces despite being able to recognise other types of visual objects. However, a 1984 study by Baur showed that even though conscious face recognition was impaired, patients with the condition showed automatic arousal (measured by a galvanic skin response measure) to familiar faces,[5] suggesting that there were two pathways to face recognition - one conscious and one unconscious.
In a 1990 paper published in the British Journal of Psychiatry,[6] psychologists Hadyn Ellis and Andy Young hypothesised that patients with Capgras delusion may have a 'mirror image' of prosopagnosia, in that their conscious ability to recognise faces was intact, but they might have damage to the system which produces the automatic emotional arousal to familiar faces. This might lead to the experience of recognising someone, while feeling something wasn't 'quite right' about them.
In 1997 Hadyn Ellis and colleagues published a study of five patients with Capgras delusion (all diagnosed with schizophrenia) and confirmed that although they could consciously recognise the faces, they did not show the normal automatic emotional arousal response.[7] The same year Hirstein and Ramachandran published a paper on a single case of a patient with Capgras delusion after brain injury that reported similar findings.[8]
It is likely that this is not the only impairment which is needed for Capgras delusion to form, however, as exactly this pattern has been reported in other patients who show no signs of delusions.[9] Ellis and colleagues suggested that a 'second factor' is therefore needed, to explain why this unusual experience is transformed into a delusional belief. This 'second factor' is thought to be an impairment in reasoning, although no definitive impairment has been found which could explain all cases.[10]
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I did one of my first term papers on this and the research for it was absolutely heartbreaking. One person who had it actually decapitated his own father because he was convinced he was some sort of robot. He thought that removing his head would reveal nothing but film inside, like a blank tape or something.
