Objective: To investigate subclinical inflammation in individuals with early drug-naive Parkinson’s disease (PD).

Background: Neutrophil-to-lymphocyte ratio (NLR) is used as a marker of subclinical inflammation. High NLR is associated with higher mortality in individuals with cardiovascular diseases, cancer and COVID-19. Preclinical studies showed that inflammation is a key driver of PD but, to date, no studies have investigated the link between NLR and PD severity and progression, or the link to imaging and non-imaging PD markers.

Method: A total of 409 people with PD were compared with 203 age-matched healthy controls (HC) from the Parkinson’s Progression Markers Initiative (PPMI) database. In the PD population, NLR was correlated with age, disease duration, severity of motor and non-motor symptoms, nigrostriatal function, and cerebrospinal fluid (CSF) biomarkers. It was then investigated whether NLR was associated with faster motor progression over a 60-month follow-up.

Results: Individuals with PD had higher NLR compared with HC (2.56±1.1 in PD vs.2.16±0.86 in HC, p<0.0001). In the PD population, higher NLR was associated with higher motor scores (Movement Disorders Society-Unified PD Rating Scale [MDS-UPDRS] Part II: r=0.111, p=0.044 and MDS-UPDRS Part III: r=0.136, p=0.006), greater dopaminergic striatal dysfunction on DaTSCAN^TM (r=–0.100, p=0.044), and higher tau-to-alpha-synuclein CSF levels (r=0.109, p=0.032). At a multivariate linear regression analysis, high NLR was associated with faster motor progression in the PD population (β=0.124, 95% confidence interval 0.225, 2.606; p=0.02).

Conclusion: Subclinical inflammation is higher in early PD, and associated with greater motor severity, worse nigrostriatal dysfunction and CSF pathology, and faster motor progression.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/subclinical-inflammation-and-parkinsons-disease/