The prevalence of Capgras syndrome in a university hospital setting

Background: Capgras syndrome (CS), the most common type of delusional misidentification syndrome, is the delusional belief that significant people in the patient's life have been replaced by identical doubles. Capgras syndrome is thought to be a rare syndrome which commonly occurs in a psychotic context. Objective: The objective of this study was to estimate the 5-year prevalence rate of CS in a university hospital in-patient setting and determine associated etiological and sociodemographic factors. Methods: All patient files and medical records were reviewed in detail for the presence of Capgras syndrome. The sociodemographic variables, clinical manifestations, and psychiatric and medical diagnoses of patients who fulfilled clinical criteria for Capgras syndrome were recorded for statistical evaluation. Results: The retrospective evaluation of patient files in 920 cases admitted to our psychiatric in-patient unit over 5 years revealed that 12 patients fulfilled the criteria for Capgras syndrome. The crude prevalence of Capgras syndrome in this population during 5-year period was 1.3% (1.8% for females, 0.9% for males). Schizophrenia (50%) was the most common psychiatric diagnosis in these patients. Only two patients presented with an organic etiology underlying Capgras syndrome. Conclusions: The results of this study indicate that Capgras syndrome is not a rare syndrome, and commonly occurs during the course of either functional or organic psychotic illness. Age seems to be an important predicting factor for the etiology of psychosis underlying Capgras syndrome