Objective: To investigate whether Parkinson’s disease (PD) motor subtypes differ in their levels of uric acid (UA), and if these differences correlate with the degree of dopamine transporter (DAT) availability.

Background: PD patients who present with tremor and maintain a predominance of tremor have a better prognosis. Similarly, PD patients with high levels of uric acid have also a better disease course. We hypothesized that UA might be involved in maintaining the less damaging tremor-dominant form of PD.

Methods: We included 139 PD patients at early stages and 75 at late stages. [123I]FP-CIT SPECTs were processed and the percentage of age-expected DAT in putamen and caudate subregions were calculated. Early stage patients were classified into tremor-onset (TO) and non-tremor onset (NTO) groups and late stage patients into tremor-dominant (TD), intermediate (I) and postural instability and gait disorder (PIGD) subtypes. The levels of UA and striatal DAT were compared between groups and the correlation between these two measures was also explored.

Results: Patients with TO had higher levels of UA (5.0 vs 4.5 mg/dL; P=0.04) and striatal DAT in posterior putamen (0.46 vs 0.36; P=0.001) and caudate (0.70 vs 0.57; P=0.007) than patients with NTO. Furthermore, UA levels significantly correlated with the levels of striatal DAT. We also found that PD patients who conserved a TD phenotype in late stages had higher levels of UA (5.3 vs 3.7 mg/dL; P<0.001) and striatal DAT than PD patients who converted to the PIGD phenotype.

Conclusions: The motor phenotype and the degree of dopamine depletion in PD may be partially driven by the levels of UA.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/lower-levels-of-uric-acid-and-striatal-dopamine-in-non-tremor-dominant-parkinsons-disease-subtype/