Researchers of a retrospective cohort from Osaka University Hospital examined predictors of atypical psychosis—marked by severe delusions, paranoia, and auditory/somatic hallucinations—after starting continuous subcutaneous infusion (CSCI) of foslevodopa/foscarbidopa in Parkinson’s disease (PD). Among 23 patients treated with CSCI, 6 (26%) developed atypical psychosis, all within 6 months; 4 discontinued CSCI. Baseline impulsive-compulsive symptoms (QUIP-CS) were significantly higher in those who developed psychosis and emerged as the sole predictor on linear regression. Because QUIP-CS is seldom used in routine care, the team evaluated PD Questionnaire (PDQ-39) items: item 27 correlated with QUIP-CS, and a five-item composite (PDQ39_sub5: items 20, 27, 29, 31, 36) showed even stronger correlation and stratified time-to-psychosis risk.
Findings were replicated in an independent PD database cohort (n=94), supporting PDQ39_sub5 as a practical proxy for impulsive-compulsive burden and psychosis risk in patients initiating advanced dopaminergic therapy. The authors argue that CSCI-induced atypical psychosis likely reflects mesolimbic circuitry involvement and dopamine dysregulation distinct from typical PD visual hallucinations. Clinically, routinely screening PDQ-39 items (or calculating PDQ39_sub5) before CSCI may help identify higher-risk individuals, enable closer monitoring in the first 6 months, and inform earlier interventions or therapy adjustments.
Reference: Ge L, Kimura Y, Kakuda K, et al. Atypical Psychosis in Parkinson Disease: A Retrospective Study on 24-Hour Continuous Subcutaneous Infusion of Foslevodopa/Foscarbidopa. Neurol Clin Pract. 2025;15(5):e200534. doi: 10.1212/CPJ.0000000000200534.
