Objective: 1) To determine serum urate and homocysteine concentration at baseline, 18 and 36 months in control and PD participants. 2) To determine if urate or homocysteine levels were predictive of changes in disease severity, Montreal Cognitive Assessment (MoCA) score or mild cognitive impairment (PD-MCI level II) over the first 36 months.

Background: Urate and homocysteine have been postulated as biomarkers for disease progression in Parkinson’s disease (PD). Baseline serum urate concentration has been shown to predict motor but not cognitive decline. The relationship between serum homocysteine concentration and cognitive and motor impairment is not known.

Methods: 154 participants with newly diagnosed PD and 99 age-matched controls participated in data collection as part of the ICICLE-PD study. Participants completed a clinical assessment, Movement Disorders Society Unified Parkinson’s disease Scale Part III (UPDRS III), MOCA and other neuropsychological assessments at baseline, 18 and 36 months. PD-MCI was diagnosed using the MDS criteria. Serum samples were drawn at the same time points and analysed for urate, homocysteine, red cell folate and vitamin B12 concentrations.

Results: Baseline urate was 331.4±83.8 and 302.7±78.0 µmol/L for control and PD participants respectively (p=0.07). Baseline homocysteine was 9.6±3.3 and 11.1±3.8 µmol/L for controls and PD participants respectively (p=0.02). Linear mixed effects modelling showed that declining UPDRS III score was predicted by age, levodopa-equivalent dose (LED) and time (p<0.05 for all). The addition of urate and homocysteine significantly improved the model (χ2=189.5, p<0.01); however only urate over time was a significant predictor of declining motor severity (β=0.2, p=0.014). There were no significant associations between change in cognition and serum urate or homocysteine concentrations.

Conclusions: Low serum urate concentration is associated with worsening motor function; however, neither urate nor homocysteine is correlated with change in cognitive outcomes. Therefore, prolonged low urate levels may be a suitable biomarker for declining motor severity even in early PD.

« Back to 2016 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/urate-and-homocysteine-changes-in-motor-and-cognitive-symptoms-in-newly-diagnosed-parkinsons-disease/