The role of uric acid in Parkinson's disease: a UK brain bank pathology-validated case-control study

Introduction Uric acid has been supposed to have a protective role in Parkinson's disease with controversial findings. This relationship has not been validated with pathology-confirmed diagnoses. This study aims to compare uric acid levels between pathology-confirmed and clinically-misdiagnosed Parkinson's disease patients over time. Methods 65 patients with an in-vivo clinical diagnosis of Parkinson's disease were enrolled from the UK Brain Bank. 33 were confirmed with post-mortem pathology analysis, while 32 were clinically misdiagnosed patients. Chart review explored uric acid levels at two timepoints (NO and N1). A repeated-measures ANOVA evaluated uric acid level variation over time and determined differences between the groups, including timespan between samples, disease duration, age at death, age of onset and sex as covariates. Results Average uric acid levels at N0 were 5.83 mg/dl (SD +/- 1.99) and 5.94 mg/dl (SD +/- 1.87) for respectively true and false positives. At N1, the values were 7.61 mg/dl (SD +/- 2.35) and 7.36 mg/dl (SD +/- 2.86) for respectively true and false positives. A significant main effect of time on uric acid levels was found (F(1, 58) = 4.303, p = 0.042, eta(2)_p = 0.069). The interaction between time and the covariates was not significant, suggesting that these variables did not influence uric acid level variation over time. No influence of the diagnostic confirmation and covariates on uric acid levels between groups was found. Conclusion While uric acid levels increase over time in Parkinson's disease patients, this increase does not differ significantly between those with confirmed and unconfirmed diagnoses, nor it is influenced by disease duration, age at death, age of onset or sex.