Abstract
BACKGROUND: Drug-induced Parkinsonism (DIP) is a predictor of future idiopathic Parkinson’s disease (PD), yet the prodromal characteristics of DIP remain unexplored.
OBJECTIVES: To compare prodromal peripheral immune cell profiles in DIP and PD.
METHODS: We applied independent regression models to evaluate the peripheral immune cell profiles in individuals with incident DIP (n = 108) and PD (n = 1055) relative to 20,070 healthy controls from the UK Biobank.
RESULTS: Approximately 9 years before diagnosis, both DIP and PD cases exhibited elevated neutrophil counts, neutrophil-to-lymphocyte ratio (NLR), and systemic immune-inflammation index (SII). Only PD cases showed reduced lymphocyte counts. After adjusting for psychiatric comorbidities, DIP-associated peripheral immune alterations were no longer significant.
CONCLUSIONS: The elevated neutrophil counts in DIP and PD suggest a shared innate immune system involvement. However, in DIP, the peripheral immune changes appear driven by psychiatric comorbidities, whereas lymphopenia may represent a distinctive prodromal biomarker of PD.