Serum Uric Acid Levels and Non-Motor Symptoms in Parkinson's Disease.

Background: Previous studies have identified low serum uric acid (SUA) levels as a risk factor for the development of Parkinson's disease (PD). Prodromal PD mainly manifests as a complex of non-motor features, but the association between SUA levels and nonmotor symptoms (NMS) burden level in advanced PD patients is poorly studied. Objective: To determine the association between SUA levels and NMS in PD patients. Methods: Data were gathered from an open label, cross sectional, study with analysis of SUA levels in 87 PD patients and were correlated to NMS through the NMS scale (NMSS). In addition, we examined the possible relation between SUA and NMS burden levels and motor scores. Results: There was a moderate negative association between SUA levels and NMSS total score (rho = -0.379, p < 0.001). In line with this, we observed that higher NMS burden was associated with lower SUA levels (p < 0.001). Within individual NMSS domains, a moderate negative correlation was observed between SUA levels and the cardiovascular/falls (rho = -0.285, p = 0.008), sleep/fatigue (rho = -0.299, p = 0.005), and miscellaneous domains (rho = -0.318, p = 0.003). Conclusion: In this observational study we observed that SUA levels were negatively associated to NMS burden in PD patients with a specific link to miscellaneous, sleep/fatigue and cardiovascular domains of the NMSS. Interestingly, we did not find a clear relation between SUA and motor scores. Future large-scale prospective studies in de novo and advanced PD are needed to evaluate and establish these associations.