Uric Acid: A Biomarker to Predict Clinical Progression of Parkinson Disease

Background: Parkinson disease (PD) is a prevalent progressive neurodegenerative disorder, affecting millions. Research continues to evolve and the medical community continues to gain knowledge surrounding the complex mechanism and pathophysiology of depletion of dopamine neurons in the substantia nigra. Researchers continue to search for new links and possible disease-modifying therapies, as treatment options for PD are primarily symptomatic. Serum uric acid, a powerful antioxidant, has been associated with a decreased risk of Parkinson disease at elevated levels in several studies, indicating a possible neuroprotective effect. Two prospective observational cohort studies established an inverse association between clinical progression of PD and urate levels, with a slower progression noted with elevated UA levels. This systematic review will examine whether uric acid levels can predict the clinical progression of Parkinson disease. Methods: An exhaustive search of literature databases was conducted using Medline-OVID, CINAHL, EBMR Multifile, and Web of Science, using the following keywords: Parkinson disease, uric acid, and disease progression. Relevant articles were included if they were primary research evaluating uric acid levels predicting progression of Parkinson disease. Each article was evaluated for quality using GRADE criteria. Results: Five articles met inclusion criteria, with two studies excluded due to being secondary analyses and to utilize the most current research. The three studies included in this systematic review are case-controlled observational studies that compared serum uric acid levels with disease progression. All studies showed an association between serum uric acid levels and disease progression of PD, with elevated levels being more favorable with a slower rate of decline. Conclusion: The results of this systematic review demonstrate the association between serum urate and the rate of PD progression, supporting future studies exploring potential disease-modifying therapy, and evaluating long-term risks of elevated serum urate levels