Abstract
The French psychiatrist Capgras in 1923 first described an example of a misidentification syndrome, in which the patient believed that familiar people had been replaced with doubles. The double had the same physical identity but a different psychological identity [1].
This is in contrast to Fregoli syndrome, where the patient identifies a familiar person in other people he encounters. In Fregoli syndrome, the recognised person takes different physical identities, but his psychological identity remains the same.
Capgras described in vivid detail the case of a 53-year-old Parisian lady, who, after losing four of her five children in infancy, believed that her husband, children, the police and medical staff caring for her had been replaced by multiple doubles. She lived through the World War I, and explained the losses in the French and British armies, by the belief that the soldiers were hidden away in the Metro, and huge numbers of other people, particularly children, were imprisoned in vast cellars underneath Paris. She believed her own identity had been changed, and that she had been kidnapped in infancy from aristocratic parents.
Over the last year, we have become aware of five cases of Capgras syndrome in our catchment area. Our team provides the inpatient and outpatient psychiatric care of the most easterly catchment area serviced by Tauranga Hospital, in the coastal Bay of Plenty, New Zealand. The catchment area population in the 1996 census was 20 936. The area consists of a rapidly expanding new suburb of the city of Tauranga and a rural area extending 55 km east of the city.
Method
The 1996 census figures were obtained from the Western Bay of Plenty and Tauranga District Councils. From these figures a population ethnicity breakdown was calculated for our catchment area. These figures were compared with those of the most westerly catchment area served by Tauranga Hospital. This westerly team is not aware of any examples of Capgras syndrome among their population. Data on admissions to the psychiatric ward and Mental Health Act committals were obtained from regularly updated hospital records, coded using ICD-9.
Results
During a 1-year period July 1998 to July 1999, five cases of Capgras syndrome were identified in the most easterly catchment area served by Tauranga Hospital. In this catchment area, according to the 1996 census figures, 19% of the population identified as Maori, 75% as European and 6% as other or non-specified. All of the cases occurred in Maori patients. Three out of five cases had become seriously threatening towards family members.
The admissions to hospital from this area over the period July 1997 to July 1999 show that Maori account for 34% of all admissions and 55% of admissions with a discharge diagnosis of schizophrenia. All readmissions were excluded from these calculations. Maori are overrepresented in the patients currently committed under the Mental Health Act, 1992. Of nine committed patients, eight identified as Maori and only one identified as European.
In the most westerly catchment area there were no identified cases of Capgras syndrome. This catchment area has a population of 23 396, where 12% identified as Maori, 87% as European and 1% as other or non-specified. A total of 20% of all admissions to this area between July 1997 and July 1999 were Maori. Maori accounted for 33% of all admissions with a discharge diagnosis of schizophrenia (readmissions not counted). Of nine committed patients, in this western catchment, only one was Maori.
Four of the five cases identified were in females. Two of the five cases described were complicated by cannabis use.
Case review: Patients with Capgras syndrome
Case one was a 49-year-old male with a 12-year history of paranoid schizophrenia. During a recent severe exacerbation he believed that a number of different people in the community were wearing his mother's face as a result of a ‘face off’ operation, and the woman who visited him in hospital was an impostor from the United Nations, looking like his mother.
Case two was a 28-year-old female with a 7-year history of schizophrenia, exacerbated in the early years by heavy cannabis use. She frequently made references to her ‘step parents’, convincing the uninitiated. Her parents, with whom she had frequent contact, were in fact both her natural parents.
Case three was a 60-year-old female with a 27-year history of schizophrenia. She claimed that her 41-year-old son, with whom she lived, was not her real son. She asserted that her real son had died in infancy and had been replaced by someone different. She believed that she had 10 other children on another planet.
Case four, a 26-year-old female with a 5-year history of brief recurrent psychotic episodes, presented acutely, believing that her deceased nephew had replaced the spirit of her 5-year-old son. She had a number of other bizarre ideas, all of which settled following admission to hospital and a small dose of chlorpromazine. There had been recent cannabis use and a range of social stressors. She represented several months later with schizophreni-form psychosis.
Case five, 23-year-old female, presented initially with a florid hallucinatory psychosis. She lacked the insight to cooperate with medication following discharge from hospital and presented 6 months later, having threatened her partner with a knife, believing that he and her father and sister were being replaced by multiple impostors.
Discussion
Five cases of Capgras syndrome were identified among our catchment population. All of the cases identified were in Maori patients.
It is possible in our group of patients that cultural differences played a role in the genesis of Capgras syndrome. The concept, for example, of a deceased person's spirit being able to enter a living person is part of normal traditional Maori belief. The stress associated with belonging to a minority, indigenous population may also be relevant, as may cannabis use.
The Maori patients in our catchment area were also overrepresented in terms of number of hospital admissions with a diagnosis of schizophrenia (19% of population accounting for 55% of admissions to hospital with a diagnosis of schizophrenia, excluding readmissions). This was also true for the westerly catchment area although less marked (12% of population accounting for 33% of hospital admissions with schizophrenia). In the easterly catchment area Maori were overrepresented in patients committed under the Mental Health Act (eight out of nine patients).
Maori were also overrepresented in hospital admissions overall for both areas.
Readmissions were excluded from these data, therefore the high proportion of Maori with a diagnosis of schizophrenia cannot be accounted for by a small number of severe cases with recurrent readmissions.
The ICD-9 codes separately for drug-induced psychosis, thus it cannot be concluded that drug abuse accounts for these figures.
It is possible that these figures illustrate the reluctance of Maori, to date, to seek early intervention for major psychotic disorder, sometimes coupled with a reluctance to accept rigorous follow-up from services which are seen as pakeha-driven (i.e. European driven).
The rates of schizophrenia were high in the Maori population in both the eastern and western catchment areas; more so in the former. It is unlikely, however, that this alone can explain the marked difference in the observed incidence of Capgras syndrome between the two areas.
The differences between the two catchments are not easily explained. Both team consultants felt they had broadly similar personal and training backgrounds, and adopted a similar approach to diagnosis. We were unaware of any differences in the presentation of schizophrenia among Maori patients compared with European patients, either among the local population or in other parts of New Zealand, of which we had extensive experience. Our explanatory hypothesis was that the author (CM) had become interested in and focused on the subject of Capgras syndrome, resulting in the ready identification of cases, and that the syndrome may, in fact, be more commonly found by anyone who cares to look closely.
On the other hand, there were tribal (iwi) differences between the two areas, possibly suggesting genetic factors may be relevant. None of the cases, however, were closely related, nor was thought to have had personal contact during the study period.
While initially considered rare, some authors suggest a prevalence of Capgras syndrome of as high as 28% among chronic psychotic patients [2].
Estimates of prevalence of Capgras syndrome vary. A USA hospital found Capgras syndrome represented 0.14% of all emergency psychiatric admissions [3].
Capgras syndrome is thought to be more common in women than in men, as was our finding.
Capgras syndrome may be associated with schizophrenia, affective disorders or organic brain disease. A review by Fortstl and Burns [4] found that out of 260 patients with misidentification syndrome, 49% had schizophrenia, 18% had organic brain disease and 11% had affective disorder.
A review of the literature regarding computed tomography, magnetic resonance imaging, electroencephalogram and neuropsychological test findings in Capgras syndrome [5] suggests a preponderance of right hemisphere abnormalities. Misidentification syndromes are commonly reported after closed head injury [6] and have been reported to occur in 20–30% of patients with Alzheimer's disease [4,7]. Mentis et al. [8] reported regional differences on positron emission tomography scans between Alzheimer patients with and without misidentification syndromes.
In three out of five of our cases, no organic factors were identified.
When Capgras first described the syndrome in 1923, he suggested facial recognition had been separated from affective response, causing the variety of responses in identification. Since then, several psychodynamic theories have been postulated to explain the genesis of this syndrome (e.g. [5,9–11].
Marked feelings of hostility towards the ‘imposter’ is common in Capgras syndrome, and occurred in three out of five of our cases. Silva et al. [12] reported eight cases of violence towards relatives of patients with Capgras syndrome. Of these eight patients, six were male. Ethnic diversity in this USA study was representative of the multi-ethnic sample population, and there was no history in any of the cases of substance abuse or physical illness. Seven out of the eight patients presented lived with the misidentified victim, as did all five in our study.
Nestor et al. [13] compared a severely violent group of patients composed primarily of psychotic patients charged with murder, with a less severely violent group composed of psychotic patients involved with property crimes.
Although both groups had similar frequencies of paranoid delusions, none of the less-severely violent group of Nestor's patients had impostor delusions, as compared with 25% of the severely violent group of patients who had impostor delusions at the time of the violent act. Of the 23 homicides, 21 involved family members. Both groups also had high rates of substance abuse.
Thompson and Swan [14] presented two cases of Capgras syndrome in which patients committed various acts of violence towards family members. Alcohol intoxication was identified as a precipitant.
Capgras syndrome frequently involves misidentification of a close relative [15] as happened in all our cases.
The above would suggest that the relatives of patients with Capgras syndrome are at high risk of severe acts of violence against them.
Conclusions
The study demonstrates Capgras syndrome is a common, not rare, phenomenon in the Maori of our catchment population. It seems possible that some ethnic groups may be more predisposed than others, and that in New Zealand, Maori patients may be particularly vulnerable. On the other hand, Capgras syndrome may merely correlate with severity of illness, and this may also explain its association with dangerousness.
Substance abuse and other organic factors may be important, and interesting lines of further research would be to establish whether cannabis and alcohol abuse, and head injury occur more commonly in the indigenous population, and whether different types of service provision can reduce the burden of serious mental illness among Maori.
Footnotes
Acknowledgements
We wish to thank the staff of Te Puna Hauora, Tauranga Hospital for their helpful comments on Maori cultural issues, and John Vickers, Consultant Psychiatrist, for his comments on general psychiatry.