Capgras syndrome: Development of the hypotheses

Objective: to trace the evolution of hypotheses concerning Capgras' syndrome. Methods: The data consist of slightly over 60 studies published between 1866 and 1991 which were selected in terms of their innovative nature and relevance to the clinical description of the syndrome and to psychodynamic, neurological and neuropsychological interpretations. Results: Two partially overlapping major stages can be identified in the evolution of hypotheses regarding the mechanisms of the syndrome. The 1st, beginning in 1923, is characterized by the predominance of psychodynamic interpretations. The 2nd, resulting from the observation of organic dysfunctions in a high percentage of cases, is distinguished by the advent of neurological interpretations, and by a few mixed hypotheses. Conclusions: Overall, this review highlights the broad diversity of viewpoints concerning the syndrome. It will be used as a basis for the following study, which is designed to show that it is possible to test each of the viewpoints experimentally.