Objective: To assess the incidence and timing of psychosis (hallucinations and delusions) in Parkinson’s disease patients receiving continuous subcutaneous infusion of foslevodopa/foscarbidopa (CSFLI).

Background: CSFLI is an effective therapy for fluctuating Parkinson’s disease, reducing OFF time and improving ON time without troublesome dyskinesia. However, neuropsychiatric complications have been reported in clinical trials, and early real-world data suggest similar risks.

Method: We conducted a retrospective observational study including all patients who initiated CSFLI treatment at our center between May 2024 and October 2025, with a minimum follow-up of six months.

Results: Fourteen patients were included (50% women; mean age 68 ± 7.7 years). Six patients (43%) developed hallucinations and/or delusions during treatment, most within the first three months (mean 2.5 months from initiation). Of these, four had prior psychotic symptoms with other therapies (mostly minor hallucinations), and one had baseline cognitive impairment. The only baseline factor significantly associated with hallucinations was longer disease duration (15.8 vs 7.5 years, p = 0.015).

Conclusion: Our study suggests that psychosis is a common complication in Parkinson’s disease patients receiving CSFLI therapy, particularly in those with longer disease duration. These findings highlight the importance of careful patient selection and early monitoring to minimize iatrogenic risks. A prospective study is ongoing to identify baseline factors that may predict the development of hallucinations during CSFLI treatment.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/psychosis-in-parkinsons-disease-patients-treated-with-continuous-subcutaneous-foslevodopa-foscarbidopa-a-real-world-observational-study/