Background: Low serum uric acid (UA) has been consistently shown to be associated with increased risk of Parkinson's disease (PD), and to predict faster motor and cognitive decline in established PD. The aim of the present study is to evaluate the relationship between serum UA and non-motor symptoms (NMS) in de novo PD.
Methods: Serum UA was measured in consecutively recruited, early drug-naïve PD patients. Exclusion criteria were: treatment with UA modifying drugs; current smoking status; metabolic or cardiac morbidity. All patients completed the NMS Questionnaire (NMSQuest). The relationship between UA levels and NMSQuest domains was explored by logistic regression, subsequently adjusted for age, gender, disease duration (months since reported motor onset) UPDRS part III, H&Y scale, and MMSE. Regression analysis studied the overall relationship between UA levels and total NMS score, and was subsequently adjusted for age, gender, disease duration UPDRS part III, H&Y scale and MMSE.
Results: Eighty PD patients were recruited. At logistic regression, higher UA levels were related to lower involvement of Attention/Memory (p = 0.004), Cardiovascular (0.009) and Sleep (p = 0.028) domains of NMSQuest. UA levels showed a significant negative correlation with total NMSQuest score at regression analysis (p = 0.001; Adjusted R-squared = 0.319).
Discussion: The present study investigated, for the first time, the relationship between NMSQuest and UA in de novo PD. Lower UA was related to higher NMSQuest total score and in particular to Attention/Memory, Cardiovascular and Sleep domains. Thus, UA seems to be a major candidate to be a valuable biomarker of such early features of PD as NMS.
Keywords: Biomarkers; Non-motor symptoms; Parkinson's disease; Urate; Uric acid.
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