Relationship between nonmotor symptoms and neutrophil-to-lymphocyte ratio in Parkinson’s disease

Purpose: The aim of this study was to investigate the relationship between neutrophil-to-lymphocyte ratio (NLR), an inflammation marker, and nonmotor symptoms, such as fatigue, sleep disturbances, and overall quality of life, in Parkinson’s disease (PD). Materials and Methods: This study included 60 patients diagnosed with PD (17 female and 43 male). Fatigue was assessed using the Parkinson’s Disease Fatigue Scale (PFS-16), sleep quality using the Parkinson’s Disease Sleep Scale (PDSS), and quality of life using the Parkinson’s Disease Questionnaire-8 (PDQ-8). Neutrophil and lymphocyte counts were extracted from the complete blood count results, and the NLR was calculated. Results: A moderate, negative correlation was observed between fatigue and sleep quality; a moderate, positive correlation was observed between quality of life, motor rating, and disease staging; a moderate, negative correlation was observed between sleep quality and quality of life; a weak, negative correlation was observed between sleep quality, motor rating, and disease staging; and a weak, positive correlation was found between quality of life, motor rating, and disease staging. No significant relationship was observed between NLR and nonmotor symptoms in PD. Conclusion: Further prospective studies with larger samples or case–control designs are warranted to explore the potential clinical utility of a simple, cost-effective biomarker, such as NLR, in assessing PD symptoms and disease progression.