Abstract
Alma Rae and Christopher Frampton, Department of Psychological Medicine, Christchurch School of Medicine, Christchurch, New Zealand:
We wish to comment on the article ‘Capgras syndrome: possibly more common among the Maori of New Zealand’ published in the October 2000 issue of the Journal [1].
The authors make a highly contentious and culturally insensitive claim, albeit hedged about with wordslike ‘possibly’, when they have failed in the most basic ways to reach acceptable standards of scholarship.
First, a detailed definition of Capgras syndrome is not provided. Had this been attempted, the authors may have discovered that it is not mentioned in DSM-IV. Kendell [2] states that it has been given more attention than it deserves, is a symptom rather than a syndrome and has no particular diagnostic significance. He also suggests that it is often based on derealization or on a change of appearance after a period of separation. In other words, Capgras ‘syndrome’ is of little real significance.
Second, it has not been validated across cultures. If Māori believe that in some instances the spirit of a person may enter the body of another, then a Māori patient exhibiting this belief cannot safely be said to be suffering from a ‘syndrome’ identified in France, another culture entirely.
Third, even if a clear definition of Capgras syndrome had been given in the text, there are no internationally agreed criteria for its identification. Nor were structured interviews used in the Tauranga area by the various clinicians whose various patients were or were not found to have the syndrome. The data on cases appear to have been gathered retrospectively in the case of the western area and we are not told whether this was the case in the eastern area. It is possible that the authors, already with an interest in the Capgras phenomenon and possibly expecting to find it more often in Māori, made some of their diagnoses prospectively thus subjecting the data to unacceptable bias.
Fourth, the cases themselves are not described in sufficient detail to permit readers to decide for themselves whether these patients had Capgras syndrome or not. In particular, case two may have had other reasons to refer to her parents as step-parents and this alone does not convince one that Capgras is present.
Fifth, there is a serious misuse of statistics in this paper. There can be no rationale for using the arbitrary geographical division of the Tauranga Hospital catchment area as a surrogate for race. The rate of Capgras syndrome in local Māori should have been calculated using the Māori population of the whole catchment area and this compared with the rate in the pakeha population of the same area. Even then, the numbers of cases are likely to be too small for any statistical significance. Furthermore, Tauranga has a very small population that is not at all typical of New Zealand demographically. No national figures for Capgras incidence are available, and so no valid comparisons can be made. In the absence of any of these prerequisites for calculating rates and probabilities, the way the authors have used percentages and numbers gives a superficial but entirely spurious credibility to a paper completely lacking any proper statistical analysis.
Last but not least are the dangers of such racially based claims. What is the casual reader going to make of this? How much more opprobrium must we heap upon the tangata whenua? (indigenous people of New Zealand). The newspapers of the land regularly trawl the medical literature looking for juicy little headlines to boost circulation, and they certainly do not include the more subtle aspects of good work let alone a critical analysis of poor scholarship. But they are always very interested in anything involving psychosis and dangerousness, in this case to the clear detriment of both the psychiatric and the indigenous populations.
This paper has taken an unsubstantiated, unprovable hunch and tried to turn it into an epidemiological study. The authors have nowhere discussed the multiple and major shortcomings of such a venture. It is very difficult to see what good the publication of this paper has achieved.