The Influence of Serum Uric Acid Level on Non-Motor Symptoms Occurrence and Severity in Patients with Idiopathic Parkinson’s Disease and Atypical Parkinsonisms—A Systematic Review

Abstract

Background and Objectives: A growing number of studies correlated higher levels of serum uric acid (UA) with both: lower risk of Parkinson’s Disease (PD) occurrence and slower progression of the disease. Similar conclusions were made where studies correlated UA with atypical Parkinsonisms (AP) progression. A few researchers have studied the issue of the influence of serum UA on the occurrence of non-motor symptoms (NMS) in PD and AP. Our systematic review is the first review completely dedicated to this matter. Materials and Methods: A comprehensive evaluation of the literature was performed to review the relationship between UA and NMS in PD and AP. The systematic review was conducted according to PRISMA Statement guidelines. The following databases were searched starting in April 2021: MEDLINE via PubMed, Embase, and Scopus. During the research, the following filters were used: >2010, articles in English, concerning humans. The study was not registered and received no external funding. Results: Seven articles meeting all inclusion criteria were included in this study. Collectively, data on 1104 patients were analyzed. A correlation between serum UA concentration and a few NMS types has been provided by the analyzed studies. In four papers, sleep disorders and fatigue were related to UA for both advanced and early PD. Other commonly appearing NMS domains were Attention/memory (4 studies), Depression/anxiety (3 studies), Cardiovascular (3 studies), Gastrointestinal (1 study), Perceptual (1 study), and Miscellaneous (1 study). For AP, no significant correlation between UA and worsening of NMS has been found. Conclusions: Based on the analyzed studies, a correlation between serum UA level and the occurrence and worsening of NMS in PD and APs cannot be definitively determined. Large-scale studies with a more diverse patient population and with more accurate methods of NMS assessment in Parkinsonism are needed.

Serum Uric Acid Levels in Parkinson’s Disease: A Cross-Sectional Electronic Medical Record Database Study from a Tertiary Referral Centre in Romania

“…Lower levels of serum UA might influence the subsequent development of mild cognitive impairment. Nevertheless, a meta-analysis on UA and non-motor features of PD, including neurocognitive impairment, did not prove an association, warranting the need for further studies [53]. UA might be excessively consumed in PD, a process putatively amplified by dopaminergic medication.…”

Uric Acid in Parkinson′s Disease: What Is the Connection?

“…In addition, serum UA was significantly lower in advanced PD compared to early PD patients, implying that low serum UA may contribute to disease severity or progression. A more recent meta‐analysis spanning seven studies evaluated the relationship between serum UA and nonmotor features and suggested that low serum UA may also contribute to neurocognitive dysfunction, fatigue, and sleep disorders 6 …”

“…Whatever the mechanisms may be, numerous studies have consistently described links between PD and uric acid (UA), the end product of purine metabolism in humans. [2][3][4][5][6] Low serum UA has been linked with a greater risk of developing PD, the severity of motor features, and faster progression of both motor and nonmotor features. The links are very strong and highly reproducible.…”

“…A more recent metaanalysis spanning seven studies evaluated the relationship between serum UA and nonmotor features and suggested that low serum UA may also contribute to neurocognitive dysfunction, fatigue, and sleep disorders. 6 However, these epidemiological case-control studies have many limitations. Because UA is measured in individuals who already have PD, UA levels may be confounded by the disease itself, its treatment, lifestyle changes related to PD, or one of many other factors linked to UA.…”

“…Several reviews summarizing the many studies linking PD and UA have been published. [2][3][4][5][6] One meta-analysis summarized 13 prior case-control studies of serum UA from a combined total of 2379 PD patients and 2267 controls from different parts of the world. 4 Serum UA was significantly and consistently lower in PD patients compared to controls.…”