Objective: To investigate the relationship between serum uric acid (UA) and the pattern of striatal dopamine depletion in drug naïve Parkinson’s disease (PD).

Background: UA is known as an antioxidant and many studies suggest that UA could have a neuroprotective effect in PD. Epidemiological studies showed low UA concentration may increase the risk of PD. Also, longitudinal studies demonstrated an inverse association between UA and PD progression.

Method: 170 patients with drug naïve PD who underwent 18F-FP-CIT PET scans were enrolled. We quantified dopamine transporter (DAT) availability in 12 striatal subregions. The patterns of striatal dopamine depletion of each patient were assessed by (1) DAT uptake of posterior putamen (PP) in more affected side, (2) Inter-subregional ratio (ISR) which was calculated by following formula: (Striatal DAT uptake in more affected side – PP in more affected side)/PP in more affected side, (3) PP in less affected side to PP in more affected side ratio (Asymmetric ratio [AR]). Serum UA was checked at first visit to Movement clinic. Since UA differs between genders, the UA level was stratified into tertile in both male and female group separately: High level (H, UA > 5.6mg/dL), intermediate level (I, 4.5 ≤ UA  ≤ 5.6 mg/dL), low level (L, UA < 4.5 mg/dL) in male and H (UA > 4.6mg/dL), I (3.6 ≤ UA ≤ 4.6 mg/dL), L (UA < 3.6mg/dL) in female. Correlation analysis about UA in all patients and ANCOVA in female and male groups respectively were done.

Results: The average age of 170 patients was 69.3±9.82 years old, disease duration was 1.81±1.95 years and ratio of male and female was 85:85. Mean of initial UA was 4.77±1.29 mg/dL. Distributions of patients in three UA groups were L:I:H 21:29:35 in male and 22:31:32 in female group. Correlation analysis about serum UA showed significant result only with gender (Pearson correlation coefficient -0.357, p<0.01). In ANCOVA, H in male group showed low ISR (p<0.007) and high PP in affected side (p<0.031). But, there was no significant difference in AR and DAT uptake in more affected striatum. There was no significant result in female group.

Conclusion: The present data demonstrated that male patients with high level of initial UA exhibited a low anterior-posterior gradient in DAT availability with relatively preserved DAT uptake in the PP, suggesting gender-specific effect of uric acid on striatal DAT availability.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/relationship-between-serum-uric-acid-and-the-pattern-of-striatal-dopamine-depletion-in-de-novo-parkinsons-disease/