A rare variant of Capgras syndrome in Alzheimer's disease

Clinical features and imaging findings in a case of Capgras syndrome

Capgras syndrome consists of the delusional belief that a person or persons have been replaced by doubles or impostors. It can occur in the context of both psychiatric and organic illness, and seems to be related to lesions of the bifrontal and right limbic and temporal regions. Indeed, magnetic resonance imaging has revealed brain lesions in patients suffering from Capgras syndrome. This case study reports the findings of a thorough diagnostic evaluation in a woman suffering from Capgras syndrome and presenting with the following clinical peculiarities: obsessive modality of presentation of the delusional ideation, intrusiveness of such ideation (that even disturbed her sleep), as well as a sense of alienation and utter disgust towards the double. These characteristics bring to mind the typical aspects of obsessive-compulsive disorder. Neuroanatomic investigation, through magnetic resonance imaging, performed on this patient showed alteration of the bilateral semioval centers, which are brain regions associated with the emotion of disgust and often show alterations in subjects suffering from obsessive-compulsive disorder. Hence, neuroimaging allows researchers to put forward the hypothesis of a common neuroanatomic basis for Capgras syndrome and obsessive-compulsive disorder, at least for cases in which the delusional ideation is associated with deep feelings of disgust and presents with a certain pervasiveness.