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disorder in which a person holds a delusional belief that an acquaintance, usually a close family member or spouse has been replaced by an identical looking imposter.
It is named after Joseph Capgras (1873-1950) a French psychiatrist who first described the disorder in a paper by Capgras and Reboul-Lachaux1,2 in 1923. 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.
This case report is taken from a 1991 report by Passer and Warnock3:
- 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earlier in the year, she had received the diagnosis of atypical psychosis because of her belief that her husband had been replaced by another unrelated man.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 hospitalise her. At times she believed her husband was her long deceased father. She easily recognised other family members and would misidentify her husband only.
There is strong neuropsychological evidence that the Capgras delusion is, at least in part, related to a loss of emotional response to familiar faces. This is in the context of generally good (although not always perfectly intact) face recognition abilities. This seems to be the reverse of prosopagnosia, a condition where conscious face recognition abilities are lost, despite sufferers still showing a covert emotional response to familiar faces, detectable by measuring (for example) skin conductance.
These results and others gained from studying the Capgras delusion have helped uncover the normal psychology of face recognition5. The study of mental illness to uncover the normal function of the mind and brain is known as cognitive neuropsychiatry and study of the Capgras delusion has been cited an early success in this field of study.
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2 Further reading
1Capgras, J, Reboul-Lachaux, J. (1923) Illusion des sosies dans un delire systematise chronique. Bulletin de la Societe Clinique de Medicine Mentale, 2, 6-16.
2Ellis HD, Whitley J, Luaute JP. (1994) Delusional misidentification. The three original papers on the Capgras, Fregoli and intermetamorphosis delusions. (Classic Text No. 17). History of Psychiatry, 5 (17), 117-46.
3Passer KM, Warnock JK. (1991) Pimozide in the treatment of Capgras' syndrome. A case report. Psychosomatics, 32 (4), 446-8.
4Forstl H, Almeida OP, Owen AM, Burns A, Howard R. (1991) Psychiatric, neurological and medical aspects of misidentification syndromes: a review of 260 cases. ''Psychological Medicine, 21(4), 905-10.
5Ellis HD, Lewis MB. (2001) Capgras delusion: a window on face recognition. Trends in Cognitive Sciences, 5(4), 149-156.