Capgras syndrome and its relationship to neurodegenerative disease.

BACKGROUND Capgras syndrome is characterized by a delusional belief that a person has been replaced by an imposter. It has been described in psychiatric and neurological (neurodegenerative and nonneurodegenerative) diseases. OBJECTIVES To determine whether the clinical and demographic features of subjects with Capgras syndrome differ when the syndrome is associated with neurodegenerative compared with nonneurodegenerative diseases, and whether features differ across different neurodegenerative diseases. DESIGN Retrospective study. SETTING Tertiary care medical center. Patients Forty-seven subjects with Capgras syndrome. RESULTS Thirty-eight of the subjects with Capgras syndrome (81%) had a neurodegenerative disease, most commonly Lewy body disease. Capgras syndrome occurred at a younger age of onset in those with a nonneurodegenerative disease (51 vs 72 years) (P < .001) co-occurring with paranoid schizophrenia, schizoaffective disorder, and methamphetamine abuse and immediately after cerebrovascular events. Of those with Capgras syndrome and Lewy body disease, 100% had visual hallucinations compared with only one of those with Alzheimer disease (14%). CONCLUSIONS Capgras syndrome is more commonly associated with neurodegenerative diseases, especially Lewy body disease, where visual hallucinations always coexist. In the absence of a neurodegenerative disease, the onset of Capgras syndrome occurs at a significantly younger age and can be associated with psychiatric disease, cerebrovascular events, and illicit drug use.