An uncommon syndrome in which a patient has a delusional belief that a person, usually a family member or friend, has been replaced by an imposter.

The aetiology of Capgras syndrome is not well understood.

It is commonly found in psychiatric disorders, namely, paranoid schizophrenia, schizoaffective disorder and affective disorders. Capgras syndrome has also been observed in a number of medical disorders, including dementia, Parkinson’s disease, central nervous system lesions, epilepsy, traumatic head injury, vitamin B12 deficiency, hepatic encephalopathy, diabetes, and hypothyroidism.

Patients with Capgras syndrome have a reasonably good prognosis. Almost two thirds of patients respond to active treatment.

Treatment should be aimed at managing the underlying cause where possible. Reported methods of treatment for Capgras syndrome have included the use of antipsychotics, antidepressants, benzodiazepines, lithium, antiepileptic mood stabilisers and electroconvulsive therapy.

The duration of Capgras syndrome can range from three days to over ten years.


1923 – First described by Capgras and Jean Reboul-Lachaux as ‘L’illusion des sosies’. The case they reported involved a woman who believed that her husband, children, neighbours and others had been replaced by doubles. [1923; 11: 6-16 ]

1929 – Levy-Valensi suggested to replace the term ‘l’illusion des sosies’ with ‘le syndrome de Capgras’.

Si Sosie est entré dans là sémiologie psychiatique, la responsabilité en incombe à M. Capgras qui le présenta trois fois au public médical (1923-1924) avec Reboul-Lachaux, Garette, Lucchini et Schiff. L’illusion des sosies est certainement, comme tout symptôme, contemporain de la morbidité psychique et j’en ai déjà relevé une observation dans Magnan (1877); mais c’est à M. Capgras que revient le mérite de l’avoir nettement individualisée, et ce serait justice de désormais l’appeler syndrome de Capgras.

Levy-Valensi, 1929: 1001

If Sosie entered into psychiatric semiology, the responsibility lies with M. Capgras who presented him three times to the medical public (1923-1924) with Reboul-Lachaux, Garette, Lucchini and Schiff. The illusion of doubles is certainly, like any symptom, contemporaneous with psychic morbidity and I have already noted an observation of it in Magnan (1877); but it is M. Capgras who deserves the credit for having clearly individualized it, and it would be fair to henceforth call it Capgras syndrome.

Levy-Valensi, 1929: 1001

1981 – The generic term ‘Delusional misidentification syndromes (DMS) was introduced by Christodoulou and Malliara-Loulakaki. There is no exact definition of this term but it has been used to encompass Capgras syndrome, Frégoli syndrome, the syndrome of subjective doubles and intermetamorphosis. [1981;14(4):245-51]

By 1976, there were 46 reported cases of Capgras syndrome in the English literature; by 1983, 170 cases; in 1987, 315 reported cases.

Early case reports describe Capgras syndrome occurring in the setting of a psychiatric illness. More recent literature has highlighted the occurrence of Capgras syndrome in many non-psychiatric organic disorders.

Associated Persons

Alternative names
  • l’illusion des sosies (illusion of doubles; illusion of counterparts)
  • Capgras delusion
  • Delusion of misidentification


Owing to the growing number of case reports of Capgras syndrome and other delusional misidentification syndromes, there are currently inconsistencies and contraindications in the classification systems of these DMS. There are ongoing attempts to reclassify these syndromes to eliminate discrepancies and inconsistent terminologies. One proposed system has suggested a classification system according to disturbances involving self, disturbance involving others and disturbance of objects.




the names behind the name

Psychiatrist in the making

BA MA (Oxon) MBChB (Edin) FACEM FFSEM. Emergency physician, Sir Charles Gairdner Hospital.  Passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |

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