Acute onset Capgras syndrome after upper respiratory tract infection: a case report on the possible role of inflammation and drug exposure.

Background: Capgras syndrome (CS) is a rare delusional disorder characterized by the delusional belief that a relative has been replaced by an identical person. This syndrome is frequently associated with psychotic disorders and neurological diseases.

Case Presentation: In this case report, we describe a 42-year-old woman who developed Capgras syndrome following a severe upper respiratory tract infection. The patient believed that her husband had been replaced by another person and was found to exhibit delusional misidentification consistent with Capgras syndrome. Paliperidone treatment was initiated and titrated up to 6 mg/day, which resulted in partial improvement of the delusions before follow-up was discontinued. Prior to the onset of Capgras symptoms, the patient had taken a combination of medications including cefuroxime, amoxicillin-clavulanic acid, ibuprofen, pseudoephedrine, and chlorpheniramine for an upper respiratory tract infection, and it is considered that these medications or the infection may have played a role in the onset of the syndrome.

Conclusion: The etiology and treatment of Capgras syndrome are still unclear and more studies are needed. This case contributes to the limited literature on Capgras syndrome by highlighting a potential temporal link between an acute upper respiratory tract infection, medication exposure, and the onset of delusional misidentification.