Low uric acid levels in patients with Parkinson's disease: evidence from meta-analysis

No causal relationship between serum urate and neurodegenerative diseases: A Mendelian randomization study

OBJECTIVE

Observational studies have shown that increased serum urate is associated with a lower risk of neurodegenerative diseases (NDs), but the causality remains unclear. We employed a two-sample Mendelian randomization (MR) approach to assess the causal relationship between serum urate and four common subtypes of NDs, including Parkinson's disease (PD), Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS).

METHODS

Serum urate data came from the CKDGen Consortium. GWAS data for PD, AD, ALS, and MS were obtained from four databases in the primary analysis and then acquired statistics from the FinnGen consortium for replication and meta-analysis. Inverse variance weighted (IVW), weighted median (WM), and MR-Egger regression methods were applied in the MR analyses. Pleiotropic effects, heterogeneity, and leave-one-out analyses were evaluated to validate the results.

RESULTS

There was no evidence for the effect of serum urate on PD (OR: 1.00, 95 % CI: 0.90-1.11, P = 0.97), AD (OR: 1.02, 95 % CI: 1.00-1.04, P = 0.06), ALS (OR: 1.05, 95 % CI: 0.97-1.13, P = 0.22), and MS (OR: 1.01, 95 % CI: 0.89-1.14, P = 0.90) risk when combined with the FinnGen consortium, neither was any evidence of pleiotropy detected between the instrumental variables (IVs).

CONCLUSION

The MR analysis suggested that serum urate may not be causally associated with a risk of PD, AD, ALS, and MS.

The relationship between uric acid levels, cognition and inflammation in a cohort of elderly subjects

BACKGROUND

Uric acid (UA) is the most powerful antioxidant found among human body fluids. With this effect, UA protects neurons from oxidant effects and ensures the continuation of the structure and functions of neuronal tissue. However, UA has effects on the immune system. This study aims to explain the relationship between UA, cognitive level and inflammation in cases with a wide spectrum of cognitive function.

METHODS

A total of 67 women and 62 men who applied to the psychiatry outpatient clinic to obtain a health report were evaluated. The cognitive states of the individuals were determined with the mini-mental state examination test (MMSE). Additionally, serum uric acid levels and simple inflammatory parameters such as CRP, sedimentation, neutrophil-lymphocyte ratio (NLR), and monocyte-lymphocyte ratio (MLR) were measured. According to the MMSE results, two groups were created. Those with an MMSE score of 24 or above formed the first group, and those with an MMSE score below 24 formed the second group.

RESULTS

While a statistically significant positive strong correlation was found between UA and MMSE in all individuals, negative correlations were found between UA and NLR and MLR in men. UA was found to be significantly lower in the group with MMSE scores below 24 and NLR values were higher in the same group.

CONCLUSION

According to these results, UA seems to have a protective effect on cognitive functions. This situation manifests itself more clearly in men. At physiological concentrations, UA may have an anti-inflammatory effect. It appears that there are complex interactions between UA, cognition, and inflammation. Particularly, men appear to be more susceptible to UA effects.

Role of antioxidants in the neurobiology of drug addiction: An update

Relationships between protective enzymatic and non-enzymatic pro-antioxidant mechanisms and addictive substances use disorders (SUDs) are analyzed here, based on the results of previous research, as well as on the basis of our current own studies. This review introduces new aspects of comparative analysis of associations of pro-antixidant and neurobiological effects in patients taking psychoactive substances and complements very limited knowledge about relationships with SUDs from different regions, mainly Europe. In view of the few studies on relations between antioxidants and neurobiological processes acting in patients taking psychoactive substances, this review is important from the point of view of showing the state of knowledge, directions of diagnosis and treatment, and further research needed explanation. We found significant correlations between chemical elements, pro-antioxidative mechanisms, and lipoperoxidation in the development of disorders associated with use of addictive substances, therefore elements that show most relations (Pr, Na, Mn, Y, Sc, La, Cr, Al, Ca, Sb, Cd, Pb, As, Hg, Ni) may be significant factors shaping SUDs. The action of pro-antioxidant defense and lipid peroxidation depends on the pro-antioxidative activity of ions. We explain the strongest correlations between Mg and Sb, and lipoperoxidation in addicts, which proves their stimulating effect on lipoperoxidation and on the induction of oxidative stress. We discussed which mechanisms and neurobiological processes change susceptibility to SUDs. The innovation of this review is to show that addicted people have lower activity of dismutases and peroxidases than healthy ones, which indicates disorders of antioxidant system and depletion of enzymes after long-term tolerance of stressors. We explain higher level of catalases, reductases, ceruloplasmin, bilirubin, retinol, α-tocopherol and uric acid of addicts. In view of poorly understood factors affecting addiction, analysis of interactions allows for more effective understanding of pathogenetic mechanisms leading to formation of addiction and development the initiation of directed, more effective treatment (pharmacological, hormonal) and may be helpful in the diagnosis of psychoactive changes.

Serum salusin-α and -β levels in patients with parkinson's disease

BACKGROUND

The etiology of Parkinson's disease (PD) is not well known and there is increasing evidence that oxidative stress also plays an important role in its pathogenesis. Salusins alpha (salusin-α) and beta (salusin-β) affect the central nervous system, vasculature, and kidneys to increase the inflammatory response in endothelial cells, stimulate oxidative stress, and increase monocyte-endothelial adhesion. Neuroinflammation and oxidative stress play roles in the etiopathogenesis of PD.

PURPOSE

To investigate whether salusin-α and -β are related to PD and whether they are correlated with the development of atherosclerosis, body mass index, disease duration, and the Parkinson's Hoehn and Yahr stage.

RESULTS

The low-density lipoprotein cholesterol (LDL-C), total cholesterol, and salusin-β levels were significantly lower and age was significantly higher in Parkinson patients compared to healthy controls (ρ < 0.005). We found a negative linear correlation between salusin-β and the Hoehn and Yahr stage (ρ < 0.001, r = -0.515) in the patients.

CONCLUSIONS

There was a relationship between salusin-β and PD and a correlation between the salusin-β levels and Parkinson's stage. A possible underlying disease mechanism is an increase in oxidative stress and decrease in neuroprotective effects due to low salusin-β levels. Therefore, the effects of salusin-β in treating Parkinson disease should be evaluated. Further studies are needed to understand the effects of salusin-β treatment on preventing or slowing the course of PD.

Urate-lowering therapy following a treat-to-target continuation strategy compared to a treat-to-avoid-symptoms discontinuation strategy in gout patients in remission (GO TEST Finale): study protocol of a multicentre pragmatic randomized superiority trial

BACKGROUND

Long-term gout treatment is based on reducing serum urate levels using urate-lowering therapy (ULT). Most guidelines recommend using a lifelong continuation treat-to-target (T2T) strategy, in which ULT is dosed or combined until a serum urate target has been reached and maintained. However, a frequently used alternative strategy in clinical practice is a treat-to-avoid-symptoms (T2S) ULT discontinuation strategy, with the possibility of restarting the medication. This latter strategy aims at an acceptable symptom state, regardless of serum urate levels. High-quality evidence to support either strategy for patients in prolonged remission while using ULT is lacking.

METHODS

We developed an investigator-driven pragmatic, open-label, multicentre, randomized, superiority treatment strategy trial (GO TEST Finale). At least 278 gout patients using ULT who are in remission (>12 months, preliminary gout remission criteria) will be randomized 1:1 to a continued T2T strategy (treatment target serum urate < 0.36 mmol/l) or switched to a T2S discontinuation strategy in which ULT is tapered to stop and restarted in case of (persistent or recurrent) flaring. The primary outcome is the between-group difference in the proportion of patients not in remission during the last 6 months of 24 months follow-up and will be analyzed using a two proportion z test. Secondary outcomes are group differences in gout flare incidence, reintroduction or adaptation of ULT, use of anti-inflammatory drugs, serum urate changes, occurrence of adverse events (with a special interest in cardiovascular and renal events), and cost-effectiveness.

DISCUSSION

This study will be the first clinical trial comparing two ULT treatment strategies in patients with gout in remission. It will contribute to more specific and unambiguous guideline recommendations and improved cost-effectiveness of long-term gout treatment. It also paves the way (exploratory) to individualized long-term ULT treatment. In this article, we elaborate on some of our trial design choices and their clinical and methodological consequences.

TRIAL REGISTRATION

International Clinical Trial Registry Platform (ICTRP) NL9245. Registered on 2 February 2021 (METC Oost-Nederland NL74350.091.20); EudraCT EUCTR2020-005730-15-NL. Registered on 11 January 2021.

Serum but not cerebrospinal fluid levels of allantoin are increased in de novo Parkinson's disease

Oxidative stress supposedly plays a role in the pathogenesis of Parkinson's disease (PD). Uric acid (UA), a powerful antioxidant, is lowered in PD while allantoin, the oxidation product of UA and known biomarker of oxidative stress, was not systematically studied in PD. We aim to compare serum and cerebrospinal fluid (CSF) levels of UA, allantoin, and allantoin/UA ratio in de novo PD patients and controls, and evaluate their associations with clinical severity and the degree of substantia nigra degeneration in PD. We measured serum and CSF levels of UA, allantoin, and allantoin/UA ratio in 86 PD patients (33 females, mean age 57.9 (SD 12.6) years; CSF levels were assessed in 51 patients) and in 40 controls (19 females, 56.7 (14.1) years). PD patients were examined using Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS), Montreal Cognitive Assessment (MoCA), Scales for Outcomes in Parkinson Disease-Autonomic (SCOPA-AUT), the University of Pennsylvania Smell Identification Test (UPSIT), one-night video-polysomnography, and dopamine transporter single-photon emission computed tomography (DAT-SPECT). Serum allantoin and allantoin/UA ratio were significantly increased in the PD group compared to controls (p < 0.001 and p = 0.002, respectively). Allantoin/UA ratios in serum and CSF were positively associated with the SCOPA-AUT score (p = 0.005 and 0.031, respectively) and RBD presence (p = 0.044 and 0.028, respectively). In conclusion, serum allantoin and allantoin/UA ratio are elevated in patients with de novo PD. Allantoin/UA ratio in serum and CSF is associated with autonomic dysfunction and RBD presence, indicating that higher systemic oxidative stress occurs in PD patients with more diffuse neurodegenerative changes.

High-Dose Ambroxol Therapy in Type 1 Gaucher Disease Focusing on Patients with Poor Response to Enzyme Replacement Therapy or Substrate Reduction Therapy

Ambroxol hydrochloride (ABX), an oral mucolytic drug available over the counter for many years, acts as a pharmacological chaperone for mutant glucocerebrosidase, albeit at higher doses. Proof-of-concept reports have been published over the past decade on all three types of Gaucher disease (GD). Here, we assess the safety and efficacy of 12 months of 600 mg ambroxol per day in three groups of Type 1 GD patients with a suboptimal response to enzyme replacement therapy (ERT) or substrate reduction therapy (SRT), defined as platelet count < 100 × 10³/L, lumbar spine bone density T-score < -2.0, and/or LysoGb1 > 200 ng/mL, and for a group of naïve patients who had abnormal values in two of these three parameters. We enrolled 40 patients: 28 ERT- or SRT-treated, and 12 naïve. There were no severe adverse effects (AEs). There were 24 dropouts, mostly due to AEs (n = 12), all transient, and COVID-19 (n = 7). Among the 16 completers, 5 (31.2%) had a >20% increase in platelet count, 6 (37.5%) had a >0.2 increase in T-score, and 3 (18.7%) had a >20% decrease in Lyso-Gb1. This study expands the number of patients exposed to high-dose ABX, showing good safety and satisfactory efficacy, and provides an additional rationale for adding off-label ABX to the arsenal of therapies that could be offered to patients with GD1 and a suboptimal response or those unable to receive ERT or SRT.

Promising biomarkers and therapeutic targets for the management of Parkinson's disease: recent advancements and contemporary research

Parkinson's disease (PD) is one of the progressive neurological diseases which affect around 10 million population worldwide. The clinical manifestation of motor symptoms in PD patients appears later when most dopaminergic neurons have degenerated. Thus, for better management of PD, the development of accurate biomarkers for the early prognosis of PD is imperative. The present work will discuss the potential biomarkers from various attributes covering biochemical, microRNA, and neuroimaging aspects (α-synuclein, DJ-1, UCH-L1, β-glucocerebrosidase, BDNF, etc.) for diagnosis, recent development in PD management, and major limitations with current and conventional anti-Parkinson therapy. This manuscript summarizes potential biomarkers and therapeutic targets, based on available preclinical and clinical evidence, for better management of PD.

Low serum uric acid levels and levodopa-induced dyskinesia in Parkinson's disease

BACKGROUND

Levodopa is the most used and effective medication for motor symptoms of Parkinson disease (PD), its long-term use is associated with the appearance of levodopa-induced dyskinesia (LID). Uric acid (UA) is believed to play an important neuroprotective role in PD.

OBJECTIVE

To investigate if serum UA levels are related with the presence of LIDs in PD patients. Also, we investigated the associations among UA levels and clinical features of PD.

METHODS

We enrolled 81 PD patients (dyskinesia = 48; no dyskinesia = 33) in the present study. A blood sample was collected to evaluate serum UA levels, clinical evaluation included the following instruments: Montreal Cognitive Assessment (MoCA), Beck Depression Inventory II (BDI-II), MDS-Unified Parkinson's Disease Rating Scale (MDS-UPDRS), Hoehn and Yahr (HY), and the sub-item 4.1 of MDS-UPDRS IV (score ≥ 1). Additional relevant clinical information was obtained by a clinical questionnaire.

RESULTS

Serum UA levels were lower in the dyskinesia group when compared with the no dyskinesia group. The same result was found in the UA levels of both men and women. The multivariate analysis showed lower uric acid levels were significantly associated with having dyskinesia (odds ratio [OR] = 0.424; 95% confidence interval [CI]: 0.221-0.746; p = 0.005). Additional analysis verified that serum UA levels are inversely correlated with depressive symptoms, disease duration, MDS-UPDRS IV and time spent with dyskinesia. A positive correlation was found with age at onset of PD symptoms.

CONCLUSIONS

The present study provides a possible role of serum UA levels in LID present in PD patients.

The glucocerebrosidase mutations and uric acid levels in Parkinson's disease: A 3-years investigation of a potential biomarker"

Background

Blood uric acid level indicates an emerging biomarker in Parkinson's disease (PD). This study aimed to evaluate longitudinal uric acid levels among different kinds of glucocerebrosidase (GBA) mutations and to compare it among sporadic PD, genetic cohort Parkinson's disease (GENPD), genetic cohort unaffected (GENUN), and healthy control (HC) patients.

Methods

We conducted a study on 654 individuals from the Parkinson's progression markers initiative (PPMI) database. Baseline characteristics, uric acid levels, movement disorder society unified Parkinson's disease rating scale III (MDS-UPDRS III), Hoehn and Yahr Parkinson stage (H&Y stage), and DaT scan specific binding ratio (SBR) data were obtained. Different GBA mutations were collected and categorized into three groups. Longitudinal measurements of uric acid and MDS-UPDRS III score were evaluated during 3-years of follow-up.

Result

GENPD cohort exhibited a greater MDS-UPDRS III score, H&Y stage, and lower SBR in the right caudate, left caudate, and right putamen compared to sporadic PD. Baseline uric acid level was similar among all groups and different GBA variants. After adjustment for age, sex, and body mass index, the uric acid level was significantly lower in the GENPD group than in HC during year 2 (P-value: 0.009). No significant longitudinal differences were detected for the MDS-UPDRS III score and three groups of GBA mutations.

Conclusion

This is the first study to assess uric acid levels and MDS-UPDRS III scores among different GBA mutation variants within 3 years of follow-up. We found similar clinical characteristics among different subtypes of GBA mutations.

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

Background and Objectives: Parkinson’s disease (PD) is a prevalent neurodegenerative condition responsible for progressive motor and non-motor symptoms. Currently, no prophylactic or disease-modifying interventions are available. Uric acid (UA) is a potent endogenous antioxidant, resulting from purine metabolism. It is responsible for about half of the antioxidant capacity of the plasma. Increasing evidence suggests that lower serum UA levels are associated with an increased risk of developing PD and with faster disease progression. Materials and Methods: We conducted an electronic medical record database study to investigate the associations between UA levels and different characteristics of PD. Results: Out of 274 datasets from distinct patients with PD, 49 complied with the predefined inclusion and exclusion criteria. Lower UA levels were significantly associated with the severity of parkinsonism according to the Hoehn and Yahr stage (r_s = 0.488, p = 0.002), with the motor complications of long-term dopaminergic treatment (r = 0.333, p = 0.027), and with the presence of neurocognitive impairment (r = 0.346, p = 0.021). Conclusions: Oxidative stress is considered a key player in the etiopathogenesis of PD, therefore the involvement of lower UA levels in the development and progression of PD is plausible. Data on the potential therapeutic roles of elevating serum UA (e.g., by precursor administration or diet manipulation) are scarce, but considering the accumulating epidemiological evidence, the topic warrants further research.

Diagnostic work up: Laboratory and biomarkers

This chapter will focus on the diagnostic work around sexual dysfunction in Parkinson's disease, especially laboratory tests and biomarkers. A number of methods to analyze if sexual dysfunction is caused by neural pathology, vascular dysfunction or other mechanisms are now available. Other methods can be used to differentiate between psychogenic/functional reasons behind sexual dysfunction and organic ones. The role of biomarkers for diagnosis, but also for understanding the reason behind and for counteracting sexual dysfunction is becoming more evident. There is also a rich and increasing number of scales and other instruments available for detecting and quantifying sexual hypo- and hyperactivity. When investigating the reason behind sexual dysfunction in patients with Parkinson's disease comorbidities should also be considered. Finally, early and pronounced sexual dysfunction might in some cases be an indication that differential diagnosis, like Multisystem Atrophy, should be thought about. All these aspects of the diagnostic procedures around sexual dysfunction in Parkinson's disease will be covered in this chapter.

Clinical Association between Gout and Parkinson's Disease: A Nationwide Population-Based Cohort Study in Korea

Background and Objectives: This retrospective cohort study aimed to investigate the association between gout and Parkinson’s disease (PD) in Korea. Materials and Methods: Overall, 327,160 patients with gout and 327,160 age- and sex-matched controls were selected from the Korean National Health Insurance Service (NHIS) database. PD incidence was evaluated by reviewing NHIS records during the period from 2002 to 2019. Patients with a diagnosis of gout (International Classification of Diseases-10 (ICD-10), M10) who were prescribed medications for gout, including colchicine, allopurinol, febuxostat, and benzbromarone for at least 90 days were selected. Patients with PD who were assigned a diagnosis code (ICD-G20) and were registered in the rare incurable diseases (RID) system were extracted. Results: During follow-up, 912 patients with gout and 929 control participants developed PD. The incidence rate (IR) of overall PD (per 1000 person-years) was not significantly different between both groups (0.35 vs. 0.36 in gout and control groups, respectively). The incidence rate ratio (IRR) was 0.98 (95% CI: 0.89–1.07). The cumulative incidence of PD was not significantly different between the groups. No association between gout and PD was identified in univariate analysis (HR = 1.00, 95% CI: 0.91–1.10, p = 0.935). HR increased significantly with old age (HR = 92.08, 198, and 235.2 for 60–69 years, 70–79 years, and over 80 years, respectively), female sex (HR = 1.21, 95% CI: 1.07–1.37, p = 0.002), stroke (HR = 1.95, 95% CI: 1.76–2.16, p < 0.001), and hypertension (HR = 1.16, 95% CI: 1.01–1.34, p = 0.04). Dyslipidemia exhibited an inverse result for PD (HR = 0.6, 95% CI: 0.52–0.68, p < 0.001). Conclusions: This population-based study did not identify an association between gout and PD. Age, female sex, stroke, and hypertension were identified as independent risk factors for PD, and dyslipidemia demonstrated an inverse result for PD.

Current advances in metabolomic studies on non-motor psychiatric manifestations of Parkinson's disease (Review)

Life expectancy has increased worldwide and, along with it, a greater prevalence of age-dependent disorders, chronic illnesses and comorbidities can be observed. In 2019, in both Europe and the Americas, dementias ranked 3rd among the top 10 causes of death. Parkinson's disease (PD) is the second most frequent type of neurodegenerative disease. In the last decades, globally, the number of people suffering from PD has more than doubled to over 6 million. Of all the neurological disorders, PD increased with the fastest rate. This troubling trend highlights the stringent need for accurate diagnostic biomarkers, especially in the early stages of the disease and to evaluate treatment response. To gain a broad and complex understanding of the recent advances in the '-omics' research fields, electronic databases such as PubMed, Google Academic, and Science Direct were searched for publications regarding metabolomic studies on PD to identify specific biomarkers for PD, and especially PD with associated psychiatric symptomatology. Discoveries in the fields of metagenomics, transcriptomics and proteomics, may lead to an improved comprehension of the metabolic pathways involved in disease etiology and progression and contribute to the discovery of novel therapeutic targets for effective treatment options.

Patients with REM sleep behavior disorder have higher serum levels of allantoin

INTRODUCTION

Rapid eye movement (REM) sleep behavior disorder (RBD) is associated with an increased risk of developing Parkinson's disease (PD). Low uric acid (UA) levels are associated with the risk of development and progression of PD. Allantoin is the major oxidation product of UA and is considered as a biomarker of oxidative stress. We aimed to compare serum levels of UA, allantoin, and allantoin/UA ratio in RBD patients with those in healthy controls, and to examine their associations with clinical severity.

METHODS

We evaluated serum levels of UA, allantoin, and allantoin/UA ratio in 38 RBD patients (one female, mean age 66.8 (SD 6.3) years) and in 47 controls (four females, 66.8 (7.6) years). All RBD patients were assessed according to an examination protocol, which included structured interview, Montreal Cognitive Assessment (MoCA), Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS), and dopamine transporter single-photon emission computed tomography (DAT-SPECT). The lower putaminal binding ratio from both hemispheres was used for analysis.

RESULTS

Mean serum allantoin concentration and allantoin/UA ratio were significantly increased in the RBD group compared to controls (2.6 (1.8) vs. 1.4 (0.7) μmol/l, p = 0.0004, and 0.008 (0.004) vs. 0.004 (0.002), p < 0.0001, respectively). There were no significant differences in UA levels between the two groups. No significant associations between any biochemical parameter and RBD duration, putaminal binding ratio on DAT-SPECT, MDS-UPDRS, or MoCA score were found.

CONCLUSION

Serum allantoin and allantoin/UA ratio are increased in RBD patients in comparison to controls, which may reflect increased systemic oxidative stress in prodromal synucleinopathy.

Associations of Lower Caffeine Intake and Plasma Urate Levels with Idiopathic Parkinson's Disease in the Harvard Biomarkers Study

Two purines, caffeine and urate, have been associated with a reduced risk of idiopathic Parkinson's disease (PD) in multiple cohorts and populations. The Harvard Biomarkers Study (HBS) is a longitudinal study designed to accelerate the discovery and validation of molecular diagnostic and progression markers of early-stage PD. To investigate whether these 'reduced risk' factors are associated with PD within this cohort, we conducted a cross-sectional, case-control study in 566 subjects consisting of idiopathic PD patients and healthy controls. Caffeine intake as assessed by a validated questionnaire was significantly lower in idiopathic PD patients compared to healthy controls in males (mean difference -125 mg/day, p < 0.001) but not in females (mean difference -30 mg/day, p = 0.29). A strong inverse association was also observed with plasma urate levels both in males (mean difference -0.46 mg/dL, p = 0.017) and females (mean difference -0.45 mg/dL, p = 0.001). Both analyses stratified for sex and adjusted for age, body mass index, and either urate level or caffeine consumption, respectively. These results highlight the robustness of caffeine intake and urate as factors inversely associated with idiopathic PD.

Mendelian Randomisation Finds No Causal Association between Urate and Parkinson's Disease Progression

BACKGROUND

Parkinson's disease (PD) is a common neurodegenerative movement disorder. Observational studies suggest higher levels of plasma urate may protect against Parkinson's risk and progression; however, causality cannot be established.

OBJECTIVES

This study set out to determine whether there is a true causal association between urate levels and PD age at onset (AAO) and progression severity using recently released PD AAO and progression genome-wide association study (GWAS) data.

METHODS

A large two-sample Mendelian randomization design was employed, using genetic variants underlying urate levels and the latest GWAS data for PD outcomes.

RESULTS

This study found no causal association between urate levels and Parkinson's risk, AAO, or progression severity.

CONCLUSIONS

Our results predict increasing urate levels as a therapeutic strategy is unlikely to benefit PD patients. © 2021 International Parkinson and Movement Disorder Society.

Plant Polyphenols as Neuroprotective Agents in Parkinson's Disease Targeting Oxidative Stress

Parkinson's disease (PD) is the second most prevalent progressive neurodegenerative disorder characterized by the degeneration of dopaminergic neurons in the human midbrain. Various ongoing research studies are competing to understand the pathology of PD and elucidate the mechanisms underlying neurodegeneration. Current pharmacological treatments primarily focused on improving dopamine metabolism in PD patients, despite the side effects of long-term usage. In recent years, it is recognized that oxidative stress-mediated pathways lead to neurodegeneration in the brain, which is associated with the pathophysiology of PD. The importance of oxidative stress is often less emphasized when developing potential therapeutic approaches. Natural plant antioxidants have been shown to mediate the oxidative stress-induced effects in PD, which has gained considerable attention in both in vitro and in vivo studies. Yet, clinical trials on natural polyphenol compounds are limited, restricting the potential use of these compounds as an alternative treatment for PD. Therefore, this review provides an understanding of the oxidative stress-induced effects in PD by elucidating the underlying events contributing to oxidative stress and explore the potential use of polyphenols in improving the oxidative status in PD. Preclinical findings have supported the potential of polyphenols in providing neuroprotection against oxidative stress-induced toxicity in PD. However, limiting factors, such as safety and bioavailability of polyphenols, warrant further investigations so as to make them the potential target for clinical applications in the treatment and management of PD.

Non-Genetic Risk Factors for Parkinson's Disease: An Overview of 46 Systematic Reviews

BACKGROUND

Numerous systematic reviews (SRs) and meta-analyses on non-genetic risk factors for Parkinson's disease (PD) development have been published with inconsistent conclusions.

OBJECTIVE

This overview of SRs aimed to summarize evidence on non-genetic factors for the development of PD from the published SRs, and explore the reasons behind the conflicting results.

METHODS

Three international databases were searched for SRs with meta-analyses summarized evidence on non-genetic factors for PD development. The Assessing the Methodological Quality of Systematic Reviews 2 tool was used to appraise the methodological quality of included SRs. Pooled effect estimations were extracted from each meta-analysis.

RESULTS

Forty-six SRs covered six categories, and more than 80 factors were included in this overview. Thirty-nine SRs (84.7%) were judged to be of critically low methodological quality. Evidence from prospective studies showed that physical activity, smoking, coffee, caffeine, tea, fat intake, ibuprofen use, calcium channel blocker use, statin use, thiazolidinediones, and high serum urate levels significantly reduced the risk of PD, while dairy intake, diabetes, hormone replacement therapy, depression, mood disorder, bipolar disorder, and aspirin use significantly increased the risk of PD. Differences in study designs (e.g., cohort studies, case-control studies) accounted for the conflicting results among included SRs.

CONCLUSION

Modifiable lifestyle factors such as physical activity and tea and coffee drinking may reduce the risk of PD, which may offer PD prevention strategies and hypotheses for future research. However, the designs of primary studies on PD risk factors and related SRs need to be improved and harmonized.

Association of sleep quality and sleep duration with serum uric acid levels in adults

OBJECTIVE

To date, the association between sleep duration or sleep quality and hyperuricemia has remained unclear. In addition, sleep duration and quality were not considered concomitantly in previous studies. Thus, this study was aimed toward an examination of the association of sleep duration and quality with uric acid level in a Taiwanese population.

METHODS

A total of 4,555 patients aged ≥18 years were enrolled in this study. The sleep duration was classified into three groups: short (<7 h), normal (7-9 h), and long (≥9 h). The Pittsburgh Sleep Quality Index (PSQI) was used to evaluate sleep quality, and poor sleep quality was defined as a global PSQI score of >5.

RESULTS

Poor sleepers were younger and had lower body mass index, blood pressure, uric acid, blood sugar, cholesterol, creatinine level, shorter sleep duration, and engaged in less exercise but had a higher white blood cell count and prevalence of smoking as compared to good sleepers. There were also differences in body mass index, blood pressure, uric acid, blood sugar, lipid profiles, and sleep quality among subjects with different sleep durations. After adjusting for other variables, poor sleep quality was associated with lower uric acid levels. In addition, short sleep duration was positively associated with higher uric acid levels.

CONCLUSIONS

Poor sleep quality was related to lower uric acid levels, whereas short sleep duration was associated with higher uric acid levels.

The Relationship Between Serum Uric Acid Levels and Clinical Features in Essential Tremor

Introduction

In this study, we aimed to investigate the effect of uric acid on the disease, its severity and progression in ET patients with partially co-clinical features with Parkinson's disease (PD).

Methods

Serum UA levels of 87 consecutive ET patients were measured and were matched according to age and sex with 87 healthy controls. Fahn-Tolosa-Marin scale was used for the severity of tremor. Sociodemographic characteristics, type of ET, duration of disease, and treatment modalities were evaluated.

Results

The mean uric acid level was calculated as 4.986±2.1458 mg/dL and 6.004±1.523 mg/dL in the patient and control groups, respectively (p≤0.005). The blood UA level of patients with sporadic (n: 61) ET was found to be lower than the familial ET (n: 26) (p≤0.005). The tremor severity of the family ET patients was lower than the sporadic ET. (n: 61) (p≤0.005). The mean blood UA level (4.429±1.216 mg/dL) in the patients with high total tremor severity scores (n: 48) was found lower than in the patients with low total tremor severity scores (n: 39) (5.673±2.106 mg/dL) (P=0.000). The serum UA level was significantly lower in the patients whose disease duration longer than 5 years than in patients whose duration of the disease was shorter than 5 years. 5.732±1.240 for ≥5 years; 6.438±0.286≤5 years) (P=0.001).

Conclusion

We hypothesize that as a result of high antioxidant properties of high serum uric acid levels, it is a biomarker that can show disease risk and progression in patients with ET as well as PD.

Blood biomarkers with Parkinson's disease clusters and prognosis: The oxford discovery cohort

Background

Predicting prognosis in Parkinson's disease (PD) has important implications for individual prognostication and clinical trials design and targeting novel treatments. Blood biomarkers could help in this endeavor.

Methods

We identified 4 blood biomarkers that might predict prognosis: apolipoprotein A1, C‐reactive protein, uric acid and vitamin D. These biomarkers were measured in baseline serum from 624 Parkinson's disease subjects (median disease duration, 1.0 years; interquartile range, 0.5–2.0) from the Oxford Discovery prospective cohort. We compared these biomarkers against PD subtypes derived from clinical features in the baseline cohort using data‐driven approaches. We used multilevel models with MDS‐UPDRS parts I, II, and III and Montreal Cognitive Assessment as outcomes to test whether the biomarkers predicted subsequent progression in motor and nonmotor domains. We compared the biomarkers against age of PD onset and age at diagnosis. The q value, a false‐discovery rate alternative to P values, was calculated as an adjustment for multiple comparisons.

Results

Apolipoprotein A1 and C‐reactive protein levels differed across our PD subtypes, with severe motor disease phenotype, poor psychological well‐being, and poor sleep subtype having reduced apolipoprotein A1 and higher C‐reactive protein levels. Reduced apolipoprotein A1, higher C‐reactive protein, and reduced vitamin D were associated with worse baseline activities of daily living (MDS‐UPDRS II).

Conclusion

Baseline clinical subtyping identified a pro‐inflammatory biomarker profile significantly associated with a severe motor/nonmotor disease phenotype, lending biological validity to subtyping approaches. No blood biomarker predicted motor or nonmotor prognosis. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Assessment of serum uric acid levels in patients with restless legs syndrome

In our study, the aim was to collect data in relation to our hypothesis that oxidative stress is effective in the etiopathogenesis of restless legs syndrome (RLS) by assessing the serum uric acid levels, an important biomarker of oxidative stress, among RLS patients. The study included a total of 281 patients with restless legs syndrome diagnosis according to the "2012 Revised International Restless Legs Syndrome Study Group Diagnostic Criteria". Disease severity was assessed according to the "International Restless Legs Syndrome Study Group Severity Scale". The control group comprised 237 healthy individuals with the same age and gender features as the control group. The result showed no statistically significant difference in the mean age and gender between RLS and control group (p = 0.923; p = 0.433). The hemoglobin, ferritin, and uric acid levels of patients with RLS were found to be low (p < 0.001). Total iron-binding capacity level was higher in patients (p < 0.01; p < 0.05). In RLS patients, the serum uric acid level was not affected by disease severity (p > 0.05). Variables affecting uric acid level in RLS patients were determined to be age, disease duration, and hemoglobin level. The hypothesis that uric acid level, accepted as a biomarker of oxidative stress, is important in the pathogenesis of restless legs syndrome is supported by our study.

Mendelian randomization study shows no causal relationship between circulating urate levels and Parkinson's disease

Objective

Observational studies have shown that increased plasma urate is associated with lower risk of Parkinson’s disease (PD), but these studies were not designed to test causality. If a causal relationship exists, then modulating plasma urate levels could be a potential preventive avenue for PD. We used a large two-sample Mendelian randomization (MR) design to assess for a causal relationship between plasma urate and PD risk.

Methods

We used a genetic instrument consisting of 31 independent loci for plasma urate on a case-control genome-wide association study data set, which included 13,708 PD cases and 95,282 controls. Individual effect estimates for each SNP were combined using the inverse-variance weighted (IVW) method. Two additional methods, MR-Egger and a penalized weighted median (PWM)-based approach, were used to assess potential bias attributed to pleiotropy or invalid instruments.

Results

We found no evidence for a causal relationship between urate and PD, with an effect estimate from the IVW method of odds ratio (OR) 1.03 (95% confidence interval [CI], 0.88–1.20) per 1-standard-deviation increase in plasma urate levels. MR Egger and PWM analyses yielded similar estimates (OR, 0.99 [95% CI, 0.83–1.17] and 0.99 [95% CI, 0.86−1.14], respectively).

Interpretation

We did not find evidence for a linear causal protective effect by urate on PD risk. The associations observed in previous observational studies may be, in part, attributed to confounding or reverse causality. In the context of the present findings, strategies to elevate circulating urate levels may not reduce overall PD risk.

Nutritional Risk Factors, Microbiota and Parkinson's Disease: What Is the Current Evidence?

Parkinson’s disease (PD) is a frequent neurodegenerative disease among elderly people. Genetic and underlying environmental factors seem to be involved in the pathogenesis of PD related to degeneration of dopaminergic neurons in the striatum. In previous experimental researches oxidative stress, mitochondrial dysfunction, homocysteine, and neuroinflammation have been reported as potential mechanisms. Among environmental factors, nutrition is one of the most investigated areas as it is a potentially modifiable factor. The purpose of this review is to provide current knowledge regarding the relation between diet and PD risk. We performed a comprehensive review including the most relevant studies from the year 2000 onwards including prospective studies, nested case-control studies, and meta-analysis. Among dietary factors we focused on specific nutrients and food groups, alcoholic beverages, uric acid, and dietary patterns. Furthermore, we included studies on microbiota as recent findings have shown a possible impact on neurodegeneration. As a conclusion, there are still many controversies regarding the relationship between PD and diet which, beside methodological differences among studies, may be due to underlying genetic and gender-specific factors. However, some evidence exists regarding a potential protective effect of uric acid, poly-unsaturated fatty acids, coffee, and tea but mainly in men, whereas dairy products, particularly milk, might increase PD risk through contaminant mediated effect.

Uric Acid and Plant-Based Nutrition

Plant-based diets (PBDs) are associated with decreased risk of morbidity and mortality associated with important noncommunicable chronic diseases. Similar to animal-based food sources (e.g., meat, fish, and animal visceral organs), some plant-based food sources (e.g., certain soy legume products, sea vegetables, and brassica vegetables) also contain a high purine load. Suboptimally designed PBDs might consequently be associated with increased uric acid levels and gout development. Here, we review the available data on this topic, with a great majority of studies showing reduced risk of hyperuricemia and gout with vegetarian (especially lacto-vegetarian) PBDs. Additionally, type of ingested purines, fiber, vitamin C, and certain lifestyle factors work in concordance to reduce uric acid generation in PBDs. Recent limited data show that even with an exclusive PBD, uric acid concentrations remain in the normal range in short- and long-term dieters. The reasonable consumption of plant foods with a higher purine content as a part of PBDs may therefore be safely tolerated in normouricemic individuals, but additional data is needed in hyperuricemic individuals, especially those with chronic kidney disease.

Cistanche extracts ameliorates the neurotoxicity induced by hydrogen peroxide in new mutant DJ-1-transfected neuroblastoma cellular models

INTRODUCTION

DJ-1 mutation is a causative reason for familial Parkinson's disease (PD). Leucine166Proline (L166P) and C106S are two important DJ-1 mutations. In this study, we established hydrogen peroxide (H₂ O₂ ) induced L166P and C106S DJ-1-transfected neuroblastoma (SH-SY5Y) cellular models of PD and investigated the effects of Cistanche extracts and key bioactive compounds, including acteoside, echinacoside, caffeic acid, and Cistanche total glycosides on these two models.

METHODS

After expressing FLAG-tagged L166P and C106S DJ-1 plasmids in Escherichia coli, the expressed plasmids were collected, treated with restriction enzyme, and identified using DNA electrophoresis. After purification, the L166P DJ-1 and C106S DJ-1 plasmids were separately transfected into SH-SY5Y cells using liposomes. Transfected SH-SY5Y cells were detected by western blotting and immunocytochemistry. Cell viability was determined using MTT assay.

RESULTS

Both western blotting and immunocytochemistry showed that L166P and C106S DJ-1 were highly expressed in the transfected SH-SY5Y cells. MTT assays showed that transfection with L166P or C106S DJ-1 reduced the viability of SH-SY5Y cells exposed to H₂ O₂ , as compared to untransfected SH-SY5Y cells. In addition, Cistanche extracts and key bioactive compounds, including acteoside, echinacoside, caffeic acid, and Cistanche total glycosides, significantly inhibited the decreases of cell viability caused by H₂ O₂ in L166P and C106S DJ-1-transfected SH-SY5Y cells.

CONCLUSIONS

These findings suggest that we successfully established sensitive and stable H₂ O₂ induced L166P DJ-1- and C106S DJ-1-transfected SH-SY5Y cell models of PD and Cistanche extracts may thus be useful for treating PD.

Association between ambient air pollution and Parkinson's disease: Systematic review and meta-analysis

Air pollution has been evaluated as a possible risk factor for Parkinson's disease (PD), but, the present results are inconsistent and have not been combined. We performed a systematic review and meta-analysis to estimate the association between long-term exposure to ambient air pollution and PD, given the nature of disease etiology. A total of 10 studies were identified by searching Web of Science, Science Direct, and PubMed before October 2017. We found a significantly increased risk of PD with 10 parts per billion (ppb) increase in nitrogen oxides (NO_x) exposure (relative risk (RR) = 1.06; 95% confidence interval (CI): 1.04, 1.09). The pooled RR for the association between carbon monoxide (CO) exposure, 1 parts per million (ppm) increment, and the risk of PD was 1.65 (95% CI: 1.10, 2.48). The pooled RRs for the association between nitrogen dioxide (NO₂) and ozone (O₃) exposure per 1 ppb increment, and the risk of PD were 1.01 (95% CI: 1.00, 1.03) and 1.01 (95% CI: 1.00, 1.02), respectively. There was a significant heterogeneity in the meta-analysis for fine particulate matter (PM_2.5), NO₂, sulfur dioxide (SO₂), and CO. We concluded that NO₂, NO_x, CO and O₃ exposure were associated with an increased risk of PD, although there is high risk of bias. The dose-response effects evaluated by high-quality studies are needed. Researches should be expanded to low- and/or middle- income countries where indoor and outdoor air pollution are high. CAPSULE: Long-term exposure to ambient NO₂, NO_x, CO and O₃ can increase the risk of Parkinson's disease.

Association between serum uric acid level and multiple system atrophy: A meta-analysis

OBJECTIVES

Lower serum uric acid (UA) levels are considered to be related to the risk to develop many neurodegenerative disorders. However, the association between serum UA level and multiple system atrophy (MSA) remains controversial. The aim of this meta-analysis was to evaluate the relationship between serum UA level and MSA.

PATIENTS AND METHODS

PubMed, Web of Science, Embase, Cochrane Library and China National Knowledge Infrastructure (CNKI) were searched for eligible studies. Standardized mean difference (SMD) and 95% confidence intervals (95% CI) were calculated in a fixed-effects model or a random-effects model when appropriate. Subgroup analyses were carried out based on gender. A total of 6 eligible studies involving 547 MSA patients and 637 healthy individuals were identified.

RESULTS

Meta-analysis results revealed that individuals with MSA had lower sera levels of UA as compared with healthy controls (pooled SMD is -0.51, 95%CI: -0.88 to -0.14; p = 0.006). The subgroup analysis to detect sex differences showed that the pooled SMD was -0.61 (95% CI: -0.82 to -0.40; p < 0.0001) for males and -0.22 (95% CI: -0.55 to 0.10; p = 0.18) for females compared with healthy controls.

CONCLUSION

Our meta-analysis revealed that lower serum level of UA is associated with an increased risk of MSA and the relationship is significant in men but not in women.

Serum uric acid levels in patients with amyotrophic lateral sclerosis: a meta-analysis

The pathogenic mechanism of ALS remains unclear. However, increasing evidence has indicated that uric acid (UA) may play a protective role in the pathogenesis of ALS. The aim of this study was to evaluate the association between serum UA levels and ALS. A comprehensive literature search in PubMed, Embase, Web of Science, and Cochrane Library was conducted up to 31st August, 2017, using keywords. A random-effects model or fixed-effects model was used to calculate the pooled estimate according to the inter-group heterogeneity. Finally, we indentified 8 case-control and 3 cohort studies. The results indicated that patients with ALS had significant decreased levels of serum UA compared to healthy controls (standardized mean difference (SMD) = -0.72, 95% CI [-0.98,-0.46], P < 0.001). Increased serum UA levels were associated with lower all-cause mortality risk among ALS patients (risk ratio (RR) = 0.70, 95% CI [0.57, 0.87], P = 0.001). To summarize, there is an inverse association between serum UA levels and risk of death among ALS patients. Randomized controlled trials with high quality are required to elucidate the role of UA on ALS.

Biomarkers for Parkinson's Disease: Recent Advancement

As a multi-factorial degenerative disease, Parkinson's disease (PD) leads to tremor, gait rigidity, and hypokinesia, thus hampering normal living. As this disease is usually detected in the later stages when neurons have degenerated completely, cure is on hold, ultimately leading to death due to the lack of early diagnostic techniques. Thus, biomarkers are required to detect the disease in the early stages when prevention is possible. Various biomarkers providing early diagnosis of the disease include those of imaging, cerebrospinal fluid, oxidative stress, neuroprotection, and inflammation. Also, biomarkers, alone or in combination, are used in the diagnosis and evolution of PD. This review encompasses various biomarkers available for PD and discusses recent advances in their development.

Uric acid and incident dementia over 12 years of follow-up: a population-based cohort study

OBJECTIVES

In patients with gout, maintaining too low serum uric acid (SUA) level with urate-lowering therapy is a concern because uric acid is thought to be neuroprotective. However, the relation between SUA and dementia remains debated. This study aimed to investigate the impact of SUA level on the incidence of dementia.

METHODS

We assessed the longitudinal association between SUA level and incident dementia (Diagnostic and Statistical Manual of Mental Disorders Version IV (DSM-IV) criteria) in a large cohort of healthy older people from the community (Three-City Dijon cohort). Additionally, we investigated the relation between SUA level and MRI markers of brain ageing (white matter hyperintensity volume (WMHV), lacunes and hippocampal volume).

RESULTS

The study sample comprised 1598 people (mean (SD) age 72.4(4.1) years, 38.3% male). During the 13,357 person-years of follow-up (median duration: 10.1 years), dementia developed in 110 participants (crude incidence rate: 8.2/1000 person-years). After multiple adjustments, the multivariate HR with the highest (≥75th percentile) versus lowest SUA level was 1.79 (95% CI 1.17 to 2.73; p=0.007). The association was stronger with vascular or mixed dementia (HR=3.66 (95% CI 1.29 to 10.41), p=0.015) than Alzheimer's disease (HR=1.55 (95% CI 0.92 to 2.61), p=0.10). There was a non-significant trend towards an association between high SUA level and extensive WMHV (p=0.10), a biomarker of small vessel disease, but not hippocampal volume (p=0.94) or lacunes (p=0.86). The association between SUA level and vascular or mixed dementia might be affected by interim strokes.

CONCLUSIONS

Risk of dementia, especially vascular or mixed dementia, may be increased with high SUA levels in elderly people.

Serum uric acid levels and multiple health outcomes: umbrella review of evidence from observational studies, randomised controlled trials, and Mendelian randomisation studies

Objective To map the diverse health outcomes associated with serum uric acid (SUA) levels.Design Umbrella review.Data sources Medline, Embase, Cochrane Database of Systematic Reviews, and screening of citations and references.Eligibility criteria Systematic reviews and meta-analyses of observational studies that examined associations between SUA level and health outcomes, meta-analyses of randomised controlled trials that investigated health outcomes related to SUA lowering treatment, and Mendelian randomisation studies that explored the causal associations of SUA level with health outcomes.Results 57 articles reporting 15 systematic reviews and144 meta-analyses of observational studies (76 unique outcomes), 8 articles reporting 31 meta-analyses of randomised controlled trials (20 unique outcomes), and 36 articles reporting 107 Mendelian randomisation studies (56 unique outcomes) met the eligibility criteria. Across all three study types, 136 unique health outcomes were reported. 16 unique outcomes in meta-analyses of observational studies had P<10-6, 8 unique outcomes in meta-analyses of randomised controlled trials had P<0.001, and 4 unique outcomes in Mendelian randomisation studies had P<0.01. Large between study heterogeneity was common (80% and 45% in meta-analyses of observational studies and of randomised controlled trials, respectively). 42 (55%) meta-analyses of observational studies and 7 (35%) meta-analyses of randomised controlled trials showed evidence of small study effects or excess significance bias. No associations from meta-analyses of observational studies were classified as convincing; five associations were classified as highly suggestive (increased risk of heart failure, hypertension, impaired fasting glucose or diabetes, chronic kidney disease, coronary heart disease mortality with high SUA levels). Only one outcome from randomised controlled trials (decreased risk of nephrolithiasis recurrence with SUA lowering treatment) had P<0.001, a 95% prediction interval excluding the null, and no large heterogeneity or bias. Only one outcome from Mendelian randomisation studies (increased risk of gout with high SUA levels) presented convincing evidence. Hypertension and chronic kidney disease showed concordant evidence in meta-analyses of observational studies, and in some (but not all) meta-analyses of randomised controlled trials with respective intermediate or surrogate outcomes, but they were not statistically significant in Mendelian randomisation studies.Conclusion Despite a few hundred systematic reviews, meta-analyses, and Mendelian randomisation studies exploring 136 unique health outcomes, convincing evidence of a clear role of SUA level only exists for gout and nephrolithiasis.

Serum uric acid levels in patients with Parkinson's disease: A meta-analysis

Background

Lower serum uric acid (UA) levels have been reported as a risk factor in Parkinson’s disease (PD). However, the results have been inconsistent so far.

Objectives

The aim of the present study was to clarify the potential relationship of uric acid with PD.

Methods

Comprehensive electronic search in pubmed, web of science, and the Cochrane Library database to find original articles about the association between PD and serum uric acid levels published before Dec 2015. Literature quality assessment was performed with the Newcastle-Ottawa Scale. Random-effects model was used to estimate the standardized mean differences (SMDs) with 95% confidence intervals (CIs). Heterogeneity across studies was assessed using I² and H² statistics. Sensitivity analyses to assess the influence of individual studies on the pooled estimate. Publication bias was investigated using funnel plots and Egger’s regression test. Analyses were performed by using Review Manager 5.3 and Stata 11.0.

Results

Thirteen studies with a total of 4646 participants (2379 PD patients and 2267 controls) were included in this meta-analysis. The current results showed that the serum UA levels in PD patients were significantly lower compared to sex and age-matched healthy controls (SMD: -0.49, 95% CI: [-0.67, -0.30], Z = 5.20, P < 0.001) and these results showed no geographic regional (Asia: SMD = −0.65, 95% CI [−0.84, −0.46], Z = 6.75, p <0.001; Non-Asia: SMD = −0.25, 95% CI [−0.43, −0.07], Z = 2.70, p = 0.007) and sex differences (women: SMD = −0.53, 95% CI [−0.70, −0.35], z = 5.98, p <0.001; men: SMD = −0.66, 95% CI [−0.87, −0.44], z = 6.03, p <0.001). Serum UA levels in middle-late stage PD patients with higher H&Y scales were significantly lower than early stage PD patients with lower H&Y scales (SMD = 0.63, 95% CI [0.36,0.89], z = 4.64, p <0.001).

Conclusions

Our study showed that the serum UA levels are significantly lower in PD and the level is further decreased as the disease progresses. Thus it might be a potential biomarker to indicate the risk and progression of PD.

Epidemiology, environmental risk factors and genetics of Parkinson's disease

Parkinson's disease (PD) is a frequent neurodegenerative disease with a premotor phase that lasts several years. Risk factors that have been linked to PD are tobacco, caffeine, black tea, pesticides and calcium channel blockers. Some risk factors may be due to inverse causality (e.g. changes in personality during the premotor phase). The genetics of PD are complex with a contribution of Mendelian (e.g. SNCA, LRRK2, Parkin, Pink1,…) and non-Mendelian factors (e.g. single nucleotide polymorphisms). Glucocerebrosidase gene mutations (Gaucher disease) are currently the strongest genetic risk factor for PD. Studying risk factors will help to better understand the pathogenesis of PD.

Low uric acid is a risk factor in mild cognitive impairment

BACKGROUND

Mild cognitive impairment (MCI) represents a transitional stage between normal aging and dementia. Uric acid is a water-soluble antioxidant found in the body. Many recent studies have found that uric acid plays an important role in cognitive impairment, although the effects of uric acid on MCI are not clear.

OBJECTIVE

The objective of this study was to explore the relationship between uric acid and MCI.

METHODS

Using a random sampling method, this study investigated 58 patients with MCI and 57 healthy elderly from January 2016 to November 2016. Demographic information was collected, the subjects were evaluated using the Mini Mental Status Examination (MMSE), and uric acid was measured in fasting venous blood.

RESULTS

A total of 57 (49.6%) participants are healthy and 58 (50.4%) participants had MCI. The uric acid level was significantly lower in the patients with MCI (292.28±63.71 μmol/L) than in the normal controls (322.49±78.70 μmol/L; P<0.05). There were significant positive correlations between the MMSE scores, for each dimension and the total score, and uric acid level (all P<0.05). Multivariate logistic regression models illustrated that uric acid was a protective factor for MCI (odds ratio =0.999, 95% CI =0.987-0.999).

CONCLUSION

A low uric acid level is a risk factor for MCI, and an appropriate increase in uric acid can be used to slow down the occurrence and development of MCI.

Elevated Serum Uric Acid Is Associated with Greater Bone Mineral Density and Skeletal Muscle Mass in Middle-Aged and Older Adults

Background and objective

Previous studies have suggested a positive link between serum uric acid (UA) and bone mineral density (BMD). In this study, we re-examined the association between UA and BMD and further explored whether this was mediated by skeletal muscle mass in a general Chinese population.

Method

This community-based cross-sectional study was conducted among 3079 (963 men and 2116 women) Chinese adults aged 40–75 years. Face-to-face interviews and laboratory analyses were performed to determine serum UA and various covariates. Dual-energy X-ray absorptiometry was used to assess the BMD and appendicular skeletal muscle mass. The skeletal muscle mass index (SMI = ASM/Height², kg/m²) for the total limbs, arms, and legs was then calculated.

Results

The serum UA was graded and, in general, was significantly and positively associated with the BMD and muscle mass, after adjustment for multiple covariates in the total sample. Compared with participants in lowest quartile of UA, those participants in highest quartile showed a 2.3%(whole body), 4.1%(lumbar spine), 2.4%(total hip), and 2.0% (femoral neck) greater BMDs. The mean SMIs in the highest (vs. lowest) quartile increased by 2.7% (total), 2.5% (arm), 2.7% (leg) respectively. In addition, path analysis suggested that the favorable association between UA and BMD might be mediated by increasing SMI.

Conclusion

The elevated serum UA was associated with a higher BMD and a greater muscle mass in a middle-aged and elderly Chinese population and the UA-BMD association was partly mediated by muscle mass.

Effects of coffee consumption on serum uric acid: systematic review and meta-analysis

OBJECTIVE

Study results on the effects of coffee consumption on serum uric acid (UA) have been conflicting. The aim of this study is to analyze the literature regarding the effect of coffee consumption on serum UA.

METHODS

We searched MEDLINE, EMBASE, the Cochrane library, and KoreaMed for all articles published before January 2015. Studies with quantitative data on coffee consumption and serum UA level were included. Coffee consumption and serum UA level were identified with/without the risk of gout.

RESULTS

Nine studies published between 1999 and 2014 were included, containing a total of 175,310 subjects. Meta-analysis demonstrated that coffee has a significantly lowering effect on serum UA, where there are gender differences in the amount of coffee required to lower serum UA. Women (4-6 cups/day) need more coffee to lower serum UA than men (1-3 cups/day). Meta-analysis showed that coffee intake of 1 cup/day or more was significantly associated with reduction of the risk of gout, with a negative correlation with the amount of daily coffee intake for both genders.

CONCLUSIONS

This is the first systematic review on the effects of coffee consumption on serum UA. Based on our study, moderate coffee intake might be advocated for primary prevention of hyperuricemia and gout in both genders.