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in which a person holds a delusional belief that an acquaintance, usually a spouse or other close family member, has been replaced by an identical-looking impostor. The 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.Forstl, H.; Almeida, O.P.; Owen, A.M.; Burns, A.; & Howard, R. (1991). Psychiatric, neurological and medical aspects of misidentification syndromes: a review of 260 cases. "Psychological Medicine" 21 (4) 905–910. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1780403&dopt=Abstract] ] Although the Capgras delusion 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 a symptom, rather than a syndrome or classification in its own rightFact|date=June 2008.

History

The Capgras delusion is named after Joseph Capgras (1873-1950), a French psychiatrist who first described the disorder in a 1923 paper by Capgras and Reboul-Lachaux.Capgras, J. & Reboul-Lachaux, J. (1923). Illusion des sosies dans un délire systématisé chronique. "Bulletin de la Société Clinique de Médicine Mentale" 2 6–16.] Ellis, H.D.; Whitley, J.; & Luaute, J.P. (1994). Delusional misidentification. The three original papers on the Capgras, Frégoli and intermetamorphosis delusions (Classic Text No. 17). "History of Psychiatry" 5 (17) 117–146. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11639277&dopt=Abstract] ] 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 "the Capgras delusion" is used as a more suitable name.

Presentation

This case is taken from a 1991 report by Passer and Warnock:Passer, K.M. & Warnock, J.K. (1991). Pimozide in the treatment of Capgras' syndrome. A case report. "Psychosomatics" 32 (4) 446–448. [http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1961860&dopt=Abstract] ]

Causes

Some of the first clues to the possible causes of the Capgras delusion were suggested by the study of brain-injured patients who had developed prosopagnosia. In this condition, patients are unable to recognize faces consciously, despite being able to recognize other types of visual objects. However, a 1984 study by Bauer showed that even though conscious face recognition was impaired, patients with the condition showed autonomic arousal (measured by a galvanic skin response measure) to familiar faces,Bauer, R.M. (1984) Autonomic recognition of names and faces in prosopagnosia: a neuropsychological application of the guilty knowledge test. "Neuropsychologia" 22, 457–469.] suggesting that there are two pathways to face recognition—one conscious and one unconscious.

In a 1990 paper published in the "British Journal of Psychiatry", psychologists Hadyn Ellis and Andy Young hypothesized that patients with Capgras delusion may have a "mirror image" of prosopagnosia, in that their conscious ability to recognize faces was intact, but they might have damage to the system which produces the automatic emotional arousal to familiar faces.Ellis, H. D., & Young, A. W. (1990) Accounting for delusional misidentifications. "Br J Psychiatry", 157, 239-248.] This might lead to the experience of recognizing someone while feeling something was not "quite right" about them.

In 1997, Hadyn Ellis and his colleagues published a study of five patients with Capgras delusion (all diagnosed with schizophrenia) and confirmed that although they could consciously recognize the faces, they did not show the normal automatic emotional arousal response.Ellis, H. D., Young, A. W., Quayle, A. H., & De Pauw, K. W. (1997) Reduced autonomic responses to faces in Capgras delusion. "Proc R Soc Lond B Biol Sci", 264, 1085-1092.]

In that same year, William Hirstein and Vilayanur S. Ramachandran reported similar findings in a paper published on a single case of a patient with Capgras delusion after brain injury.Hirstein, W., & Ramachandran, V. S. (1997) Capgras syndrome: a novel probe for understanding the neural representation of the identity and familiarity of persons. "Proc R Soc Lond B Biol Sci", 264, 437-444."] Ramachandran also portrays this case in his book "Phantoms in the Brain". [cite book |last=Ramachandran |first=V. S |authorlink= Vilayanur S. Ramachandran |coauthors= Blakeslee S.|title=Phantoms in the Brain |year=1998 |publisher=Harper Perennial |location=Great Britain |isbn=10-1-85702-895-3 ] Since the patient was capable of feeling emotions and recognizing faces but could not feel emotions when recognizing familiar faces, Ramachandran hypothesizes that the origin of Capgras syndrome is a disconnection between the temporal cortex, where faces are usually recognized (see temporal lobe), and the limbic system, involved in emotions. Because the patient could not put together memories and feelings, he believed objects in a photograph were new on every viewing, even though they normally should have evoked feelings (e.g., a person close to him, a familiar object, or even himself). Ramachandran therefore believed there was a relationship between Capgras syndrome and a more general difficulty in linking successive episodic memories, since it is believed that emotion is critical for creating memories.

It is likely that more than an impairment of the automatic emotional arousal response is necessary to form Capgras delusion, as the same pattern has been reported in patients showing no signs of delusions.Tranel D, Damasio H, Damasio A (1995) Double dissociation between overt and covert face recognition. "Journal of Cognitive Neuroscience", 7, 425-432.] Ellis and colleagues suggested that a second factor explains 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 to explain all cases.Davies, M., Coltheart, M., Langdon, R., & Breen, N. (2001) Monothematic delusions: Towards a two-factor account. Philosophy, Psychiatry, and Psychology, 8, 133-158.]

Fiction

*The narrator of Rivka Galchen's 2008 novel "Atmospheric Disturbances", himself a psychologist, believes his wife has been replaced by a "simulacrum" or "impostress".
*The novel "The Body Snatchers" begins with several people going to the town doctor, convinced that their loved ones have been replaced with exact replicas of themselves.
*The Capgras delusion plays an important part in Richard Powers's 2006 novel "The Echo Maker", winner of the National Book Award.
*In Shirley Jackson's short story "The Beautiful Stranger", the protagonist begins with the delusion that her husband has been replaced and is ultimately unable to recognize her own house.
*An explanation of the Capgras delusion serves as an important plot turn in Neil Gaiman's short story entitled "Foreign Parts" found in the "Smoke and Mirrors" collection.
*The character of Debbie in Kate Atkinson's "Human Croquet" may suffer from this, and the syndrome is mentioned about halfway through the book.
*An example of the Capgras delusion (and possibly a parody of the latter genre) occurs in "The Outward Urge", where an astronaut develops the delusion that his colleague is a Martian.
*Th Capgras delusion was used as the reason for a murder in the plot of an episode of the American television crime drama "".
*In the film "Empire of the Wolves", the female lead initially appears to suffer from Capgras delusion, when she fails to recognise her husband and later suspects he might have undergone cosmetic surgery.
*The role-playing game "Exquisite Replicas" deals with things and people being replaced by identical copies, a phenomenon that only a few people can perceive. This may be a reference to the Capgras delusion.
*In the video game "Eternal Darkness", Maximilian Roivas succumbs to the Capgras delusion, eventually believing that his servants have been replaced with demons.

ee also

*Cognitive neuropsychiatry
*Face perception
*Fregoli delusion
*Joseph Capgras
*Monothematic delusion
*Prosopagnosia, or face-blindness

References

External links

* [http://www.damninteresting.com/?p=793 An Impostor in the Family] on [http://damninteresting.com damninteresting.com]
* [http://www.cbc.ca/arts/story/2007/08/08/ot-rosato-070808.html Trial of former SCTV/SNL comic Tony Rosato] , with [http://ahp.yorku.ca/?p=110 Capgras lit review]
* [http://www.nytimes.com/2007/09/11/health/views/11case.html?ei=5090&en=a8160770c501d6f3&ex=1347163200&adxnnl=1&partner=rssuserland&emc=rss&adxnnlx=1189883601-Ax9flmbLvUo23/n8VIm4jA&pagewanted=print When a "Duplicate" Family Moves In] - Article in the "New York Times Magazine" by Carol W. Berman, MD.
* [http://www.ted.com/talks/view/id/184 Vilayanur Ramachandran touches on Capgras at TED]