Challenging the impostor: a scoping review of the pharmacological management of Capgras syndrome in Parkinson’s disease and Lewy bodies dementia

Introduction: Capgras syndrome (CS) is a delusional misidentification phenomenon increasingly reported in patients with Parkinson’s disease (PD) and Lewy Body Dementia (LBD). Aim of the present scoping review was to provide an overview on current evidence on the pharmacological treatment of CS in PD and LBD, identifying knowledge gaps in the literature. Methods: The following databases were consulted: PubMed, Google Scholar, the Cochrane Database and Web of Science. Results: The search query covered a time period from 1976 until 2022. Fourteen studies on PD (11 single case reports, 3 case series) and five on LBD (all single case reports) met the inclusion criteria. Most PD patients with CS had cognitive decline and visual hallucinations, and were managed by reducing dopaminergic therapy and prescribing neuroleptics (quetiapine, clozapine or pimavanserin), which often resulted in improvement. Neuroleptics have also been used in LBD, but with variable efficacy. Conclusion: Although neuroleptics and dopaminergic dose adjustments appear to be beneficial for CS in PD and LBD, robust evidence is lacking. Future prospective studies are essential to establish evidence-based guidelines for this challenging syndrome.