Uric acid is associated with the prevalence but not disease progression of multiple system atrophy in Chinese population

Sex differences in alpha-synucleinopathies: a systematic review

Background

Past research indicates a higher prevalence, incidence, and severe clinical manifestations of alpha-synucleinopathies in men, leading to a suggestion of neuroprotective properties of female sex hormones (especially estrogen). The potential pathomechanisms of any such effect on alpha-synucleinopathies, however, are far from understood. With that aim, we undertook to systematically review, and to critically assess, contemporary evidence on sex and gender differences in alpha-synucleinopathies using a bench-to-bedside approach.

Methods

In this systematic review, studies investigating sex and gender differences in alpha-synucleinopathies (Rapid Eye Movement (REM) Behavior Disorder (RBD), Parkinson's Disease (PD), Dementia with Lewy Bodies (DLB), Multiple System Atrophy (MSA)) from 2012 to 2022 were identified using electronic database searches of PubMed, Embase and Ovid.

Results

One hundred sixty-two studies were included; 5 RBD, 6 MSA, 20 DLB and 131 PD studies. Overall, there is conclusive evidence to suggest sex-and gender-specific manifestation in demographics, biomarkers, genetics, clinical features, interventions, and quality of life in alpha-synucleinopathies. Only limited data exists on the effects of distinct sex hormones, with majority of studies concentrating on estrogen and its speculated neuroprotective effects.

Conclusion

Future studies disentangling the underlying sex-specific mechanisms of alpha-synucleinopathies are urgently needed in order to enable novel sex-specific therapeutics.

Serum Uric Acid Levels in Neurodegenerative Disorders: A Cross-Sectional Study

Background: Excessive oxidative stress may contribute to neurodegeneration by leading to protein aggregation and mitochondrial dysfunction. Uric acid (UA) is an important endogenous antioxidant that protects against oxidative stress, yet its exact role in neurodegeneration remains unclear. Objective: To explore the performance of serum UA in neurodegenerative disorders. Methods: A total of 839 controls and 840 patients, including Alzheimer’s disease (AD), Parkinson’s disease (PD), multiple system atrophy (MSA), progressive supranuclear palsy (PSP), frontotemporal dementia (FTD), dementia with Lewy bodies (DLB), motor neuron disease (MND), Creutzfeldt-Jakob disease (CJD), and mixed dementia (MixD) were enrolled. Fasting serum UA levels were measured in all participants and compared between patients and controls. Linear regression models were utilized to explore possible relationships of serum UA with cognition, disease duration, age, and age of onset. Results: Compared to controls (355.48 ± 85.38 μmol/L), serum UA was significantly lower in AD (291.29 ± 83.49 μmol/L, p < 0.001), PD (286.95 ± 81.78 μmol/L, p < 0.001), PSP (313.32 ± 88.19 μmol/L, p < 0.001), FTD (313.89 ± 71.18 μmol/L, p = 0.001), and DLB (279.23 ± 65.51 μmol/L, p < 0.001), adjusting for confounding factors including age, gender, education, etc. In addition, serum UA was positively correlated with cognitive levels in all patients (Mini-Mental State Examination: r = 0.136, p = 0.001; and Montreal Cognitive Assessment Scale: r = 0.108, p = 0.009). Conclusion: Decreased levels of serum UA were correlated with AD, PD, PSP, FTD, and DLB, offering significant potential as a promisingly relevant, less-invasive marker of multiple neurodegenerative disorders.

Fatigue prevalence and associated factors in patients with multiple system atrophy

OBJECTIVE

Fatigue was reported a determinant of poor quality of life in multiple system atrophy (MSA) patients. This study aimed to determine fatigue prevalence and associated demographic, motor, and non-motor symptoms in MSA patients.

MATERIALS AND METHODS

A total of 174 MSA patients met "Probable" diagnostic criteria were included in this cross-sectional study. Fatigue Severity Scale (FSS) was used to measure fatigue prevalence. Unified MSA Rating Scale (UMSARS), Non-Motor Symptoms Scale (NMSS), Hamilton Depression Rating Scale-17 (HDRS-17), Hamilton Anxiety Scale (HAMA), Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), REM Sleep Behavior Disorder Screening Questionnaire (RBDSQ), and Mini-Mental State Exam (MMSE) were used for comprehensive clinical assessments. Nonparametric Mann-Whitney or Pearson's chi-square test was used to compare the patient score with or without fatigue (defined as a mean FSS score≥4). Binary logistic regression analysis was performed to determine features independently associated with the presence of fatigue.

RESULTS

Fifty (28.7%) patients enrolled reported fatigue. Results of multivariate analysis revealed that anxiety (OR = 3.01, 95% CI = 1.43-6.31), excessive daytime sleepiness (OR = 2.70, 95% CI = 1.23-5.90), and use of sleep medicine (OR = 3.58, 95% CI = 1.39-9.24) were significantly associated with fatigue in MSA patients.

CONCLUSIONS

Fatigue is common in our MSA patients. Anxiety, excessive daytime sleepiness, and current sleep medicine use may be associated with an increased risk of fatigue. However, the severity of motor symptoms may not be associated with fatigue. Our findings highlight the need to identify, investigate, and treat fatigue in MSA.

Serum Cystatin C as a Potential Predictor of the Severity of Multiple System Atrophy With Predominant Cerebellar Ataxia: A Case-Control Study in Chinese Population

Objective: Multiple system atrophy (MSA) is a serious neurodegenerative disease that is charactered by progressive neurological disability. The aim of this study was to investigate the correlation of serum oxidant factors with the severity of MSA.

Methods: A total of 52 MSA patients and 52 age- and gender- matched healthy subjects were retrospectively enrolled in this study. Enzymatic colorimetric methods were used to assay the concentrations of uric acid (UA), serum creatinine (Scr), blood urea nitrogen (BUN), and cystatin C (Cys-C). Disease severity was evaluated by the Unified Multiple System Atrophy Rating Scale (UMSARS). The disease progression rate was defined by the change in UMSARS-IV (global disability score, GDS) over a 1-year period.

Results: Comparisons between the two groups revealed that there were no significant differences in terms of serum Scr (70.81 ± 13.88 vs. 70.92 ± 14.19 μmol/L, p = 0.967). However, the serum levels of the other three biomarkers were significantly higher in the MSA patients (UA: 325.31 ± 84.92 vs. 291.19 ± 64.14 μmol/L, p = 0.023; BUN: 5.68 ± 1.67 vs. 4.60 ± 1.24 mmol/L, p < 0.001; Cys-C: 0.96 ± 0.15 vs. 0.89 ± 0.14 mg/L, p = 0.024). In addition, Pearson correlation analyses revealed that only serum Cys-C was significantly correlated to GDS (r = 0.281, p = 0.044). Subgroup analysis further demonstrated that serum Cys-C was the only factor that was positively associated with the disease severity in patients with MSA and predominant cerebellar ataxia (MSA-C) (r = 0.444, p = 0.018); there was no significant association in MSA patients with predominant Parkinsonism (MSA-P) (r = 0.118, p = 0.582). MSA-C patients with severe disability were shown to express higher serum levels of Cys-C than patients with mild disability (1.03 ± 0.13 vs. 0.88 ± 0.12 mg/L, p = 0.009). Finally, Kaplan-Meier plots revealed a significant difference in the 5-year probability of survival from severe disability between MSA-C patients with high- and low-concentrations of serum Cys-C (Log-rank test: X² = 4.154, p = 0.042). ROC curve analysis confirmed that serum Cys-C exhibits good performance as a biomarker (AUC = 0.847).

Conclusion: Our research indicated that oxidative stress plays a vital role in MSA. Serum Cys-C represents a potential prognostic biomarker to evaluate the severity of disease in patients with MSA-C.

Urate is closely linked to white matter integrity in multiple system atrophy

Objective

We aimed to investigate the association of the serum urate level with cortical thickness and white matter integrity in multiple system atrophy (MSA).

Methods

We recruited 75 MSA patients and 42 controls who underwent brain MRI and measured serum urate level at baseline. Using cortical thickness and tract‐based spatial statistics analyses, we investigated the correlation between serum urate levels and cortical thickness or diffusion tensor imaging (DTI) measures in controls and MSA patients. Interaction effects were analyzed to find different patterns of correlation according to sex and clinical subtype. We evaluated the relationship between serum urate levels, DTI measures, and total UMSARS score, using path analysis.

Results

Serum urate levels showed a positive correlation with FA values in the corpus callosum and a negative correlation with MD values in widespread regions including cerebellar, brainstem, and cerebral white matter in patients with MSA. Both sexes showed a negative correlation between serum urate levels and MD values without significant interaction effect. In subgroup analysis according to subtype, patients with cerebellar subtype showed a negative correlation. Serum urate levels did not correlated with cortical thickness. Path analysis showed that MD values in middle and inferior cerebellar peduncle mediated the association between serum urate level and total UMSAR score.

Interpretation

The present study demonstrated that serum urate levels played a pivotal role in white matter disintegrity and clinical disability in MSA. It would provide an evidence of the role of urate as a potential neuroprotective factor against white matter neurodegeneration in MSA.

Multiple System Atrophy (MSA) and smoking: a meta-analysis and mechanistic insights

BACKGROUND

The association between cigarette smoking and multiple system atrophy (MSA) has been debated. We conducted a systematic review and a meta-analysis to investigate this link.

RESULTS

We identified 161 articles from database searching and bibliographic review. Five case-control studies satisfied the inclusion and exclusion criteria, and 435 and 352 healthy controls and MSA patients were examined. The prevalence of MSA amongst ever smokers was lower compared to never smokers (aOR=0.57; 95% CI, 0.29-1.14), although this result did not reach statistical significance. This was also observed for current and former smokers, with a stronger association for current smokers (aOR=0.63 vs aOR=0.96).

CONCLUSIONS

There is a suggestion that smoking protects against MSA. Prospective studies in larger patient cohorts are required to further evaluate the cause-effect relationship and functional studies in cellular and animal models will provide mechanistic insights on their potential etiologic links.

METHODS

PubMed and Cochrane Library were searched from inception to July 7, 2019 to identify case-control studies that analyzed smoking as an environmental risk or protective factor for MSA. Two authors independently extracted data and performed risk-of-bias and quality assessment. The random-effects model was assumed to account for between-study variance when pooling the crude and adjusted odds ratios.

Diagnostic utility of fluid biomarkers in multiple system atrophy: a systematic review and meta-analysis

BACKGROUND

Multiple system atrophy (MSA) is an adult onset, fatal neurodegenerative disease. However, no reliable biomarker is currently available to guide clinical diagnosis and help to determine the prognosis. Thus, a comprehensive meta-analysis is warranted to determine effective biomarkers for MSA and provide useful guidance for clinical diagnosis.

METHODS

A comprehensive literature search was made of the PubMed, Embase, Cochrane and Web of Science databases for relevant clinical trial articles for 1984-2019. Two review authors examined the full-text records, respectively, and determined which studies met the inclusion criteria. We estimated the mean difference, standard deviation and 95% confidence intervals.

RESULTS

A total of 28 studies and 11 biomarkers were included in our analysis. Several biomarkers were found to be useful to distinguish MSA patients from healthy controls, including the reduction of phosphorylated tau, α-synuclein (α-syn), 42-amino-acid form of Aβ and total tau (t-tau), the elevation of neurofilament light-chain protein (NFL) in cerebrospinal fluid, the elevation of uric acid and reduction of homocysteine and coenzyme Q10 in plasma. Importantly, α-syn, NFL and t-tau could be used to distinguish MSA from Parkinson's disease (PD), indicating that these three biomarkers could be useful biomarkers in MSA diagnosis.

CONCLUSION

The findings of our meta-analysis demonstrated diagnostic biomarkers for MSA. Moreover, three biomarkers could be used in differential diagnosis of MSA and PD. The results could be helpful for the early diagnosis of MSA and the accuracy of MSA diagnosis.

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 level is linked to the disease progression rate in male patients with multiple system atrophy

OBJECTIVES

Multiple system atrophy (MSA) is a progressive neurodegenerative disorder that may be caused in part by oxidative stress. Uric acid (UA) protects neurons in neurodegenerative disorders via antioxidative effects. The aim of this study was to investigate the relationship between the serum UA concentration and disease progression in MSA patients.

PATIENTS AND METHODS

A total of 53 Japanese MSA patients were enrolled in this study. The disease progression rate was estimated by the rate of global disability scale change per year. The relationship between the serum UA concentration and disease progression was assessed by Spearman's correlation analysis. Disease progression depending on the UA concentration was also estimated by multivariate logistic regression analysis.

RESULTS

MSA patients with the highest serum UA concentration had lower disease progression rates than those with the lowest concentration. Spearman's correlation analysis showed an inverse correlation between the serum UA concentration and disease progression in male patients. Multivariate logistic regression analysis confirmed that the UA concentration was independently related to disease progression only in male patients.

CONCLUSION

These results suggest that serum UA may be associated with disease progression in male patients with MSA.

Serum uric acid levels and freezing of gait in Parkinson's disease

Uric acid (UA) is a natural antioxidant and iron scavenger in the human body, which has been hypothesized to exert an anti-oxidative effect in Parkinson's disease (PD). This study aimed to investigate the relationship between serum UA levels and freezing of gait (FOG) in PD. A total of 321 Chinese PD patients with fasting serum UA evaluated were included in the cross-sectional study. Demographics, clinical features, and therapeutic regimen were collected. The Unified PD Rating Scale (UPDRS) III and Hoehn and Yahr (H and Y) stage were used to evaluate the severity of disease, and the Frontal Assessment Battery (FAB) and Montreal Cognitive Assessment (MoCA) scales were used to assess the cognitive function. Patients with FOG showed lower proportion of male, longer disease duration, lower body mass index, lower concentrations of serum UA, higher total levodopa equivalent daily dosage, higher UPDRS III score, greater median H and Y stage, lower scores of FAB and MoCA, and higher frequencies of motor fluctuation, dyskinesia, falls, and festination compared to patients without FOG (P < 0.05). The binary logistic regression model indicated that high UPDRS III score (OR = 1.049, P < 0.001), fluctuation (OR = 2.677, P = 0.035), dyskinesia (OR = 6.294, P = 0.003), festination (OR = 3.948, P < 0.001), falls (OR = 7.528, P < 0.001), and low serum UA levels (OR = 0.990, P < 0.001) were associated with FOG. Our study suggests that low serum UA concentration is associated with the occurrence of FOG in PD.

Oxidative Stress and Environmental Exposures are Associated with Multiple System Atrophy in Chinese Patients

OBJECTIVE

Oxidative stress is involved in the pathogenesis of multiple system atrophy (MSA). The aim of this study is to examine oxidant biomarkers including homocysteine (Hcys), bilirubin, uric acid, lipids, and potential environmental risk factors and to ascertain whether these data correlate with MSA in a Chinese population.

METHODS

In this study, serum levels of Hcys, bilirubin, uric acid, and lipids were studied in 55 MSA patients and 76 healthy controls (HCs). Education, anti-parkinsonian agent usage, smoking, drinking, farming, and living area of the subjects also were analyzed. The Unified MSA Rating Scale (UMSARS), Hoehn & Yahr stage, International Cooperative Ataxia Rating Scale, and Mini-Mental State Examination were used to assess the disease severity, the parkinsonism, ataxia, and the cognitive ability of MSA, respectively.

RESULTS

The levels of Hcys were higher (p<0.001) and those of total bilirubin (p=0.007), indirect bilirubin (p=0.011), and total cholesterol (p=0.046) were lower in MSA patients than in healthy controls, whereas uric acid levels did not differ significantly between MSA and healthy controls. Moreover, Hcys levels in MSA patients had positive correlations with illness duration (r s =0.422, p=0.001) and UMSARS-I (r s =0.555, p<0.001), respectively. High-density lipoprotein cholesterol levels were negatively correlated with UMSARS-I (r s =-0.325, p=0.015). Farming was more frequent in MSA patients (1-20 years: odds ratio, 6.36; p20 years: odds ratio, 10.26; p=0.001), whereas current smoking was less frequent (odds ratio, 0.13, p=0.002).

CONCLUSIONS

Elevated Hcys and decreased high-density lipoprotein cholesterol may be associated with the disease severity of MSA. Environmental exposures such as farming and smoking may contribute to the occurrence but not the progression of MSA.

Serum uric acid levels in Parkinson's disease and related disorders

OBJECTIVE

Serum uric acid (UA) levels are reported to be decreased in patients with Parkinson's disease (PD) and multiple system atrophy (MSA). However, clinical correlates of serum UA levels are still unclear in PD-related disorders. We conducted a cross-sectional study to evaluate the associations between serum UA levels and disease duration, disease severity, and motor function among PD, MSA, and progressive supranuclear palsy (PSP) patients.

METHODS

A total of 100 patients with PD, 42 patients with MSA, 30 patients with PSP, and 100 controls were included in this study. Serum UA levels were determined, and associations among serum UA levels and disease duration, disease severity, and motor function in PD, PSP, and MSA patients were evaluated.

RESULTS

Serum UA levels were significantly lower in male PD, MSA, and PSP patients compared with the controls, but not in female patients. Serum UA levels were negatively correlated with disease duration and severity in MSA and PSP patients, but no correlations were observed in PD patients. The serum UA levels were significantly decreased in the tauopathy group (PSP patients) compared with the synucleinopathy group (PD and MSA patients) after adjusting for age, gender, and body mass index.

CONCLUSION

We found decreased serum UA levels in male patients with PD-related disorders (PD, MSA, and PSP) compared with male controls, and significant correlations between serum UA levels and disease severity in MSA and PSP patients.

Plasma marker of tissue oxidative damage and edaravone as a scavenger drug against peroxyl radicals and peroxynitrite

The percentage of the plasma oxidized form of coenzyme Q10 in the total amount of coenzyme Q10 (%CoQ₁₀) is a useful marker of oxidative stress in the circulation. Plasma free fatty acids and their composition can be used as markers of tissue oxidative damage, as demonstrated in patients suffering from a wide variety of diseases and in humans and rats under oxidative stress. Edaravone was approved for the treatment of stroke in Japan in 2001 and its mechanism of action is based on scavenging lipid peroxyl radicals. In 2015, edaravone was also approved for the treatment of ALS patients. Edaravone functions therapeutically as a scavenger of peroxynitrite, as demonstrated by the finding that its administration raises plasma uric acid levels and decreases 3-nitrotyrosine in cerebrospinal fluid.

Association of serum uric acid level with cognitive function among patients with multiple system atrophy

BACKGROUND AND OBJECTIVE

Oxidative stress is involved in the pathogenesis of multiple system atrophy (MSA) and cognitive impairment. Uric acid has an anti-oxidative effect. Our objective is to clarify the correlations between serum uric acid and cognitive function as well as frontal lobe function in Chinese MSA patients.

METHODS

All of MSA patients were evaluated using Addenbrooke's Cognitive Examination-Revised (ACE-R), Frontal Assessment Battery (FAB), and Unified MSA Rating Scale (UMSARS). The fasting serum uric acid concentrations of MSA patients were measured.

RESULTS

A total of 89 probable MSA patients with a mean age of 58.6 ± 10.0 years old and disease duration of 2.6 ± 1.5 years were included. Thirty-three patients (37.1%) had global cognitive deficits according to ACE-R. Based on FAB, 35 patients (39.3%) had frontal lobe dysfunction. After adjusting for educational years, patients with cognitive deficits had lower uric acid level than patients without cognitive deficits. Patients with frontal lobe dysfunction had lower uric acid level after adjusting for UMSARS scores. In a forward multiple linear regression, uric acid level and educational years were the variables predicting the ACE-R score (F=36.540, R(2)=0.459, p=0.0001), uric acid accounting for 14% of the total variables. Uric acid was the only variable contributing to the FAB score (F=18.551, R(2)=0.176, p=0.0001).

CONCLUSION

Our study suggested that low level of serum uric acid was associated with cognitive deficits in MSA. Low uric acid level predicting cognitive decline in MSA needs more studies.

Contra-Directional Expression of Serum Homocysteine and Uric Acid as Important Biomarkers of Multiple System Atrophy Severity: A Cross-Sectional Study

HIGHLIGHTS

Serum Hcy was higher in MSA patients when compared to healthy subjects, particularly in male patients.Serum UA was lower in MSA patients when compared healthy subjects, particularly in male patients.Serum Hcy levels were significantly positively correlated with the severity of MSA.The ROC curve for the combination of Hcy and UA showed potential diagnostic value in discriminating MSA from healthy subjects.

AIM

There is evidence suggesting that inflammatory responses play a critical role in the pathogenesis of multiple system atrophy (MSA). Whether inflammatory mediators can be used as reliable biomarkers to detect the severity and progression of MSA remains largely unknown.

METHODS

We performed a cross-sectional study that included 47 patients with MSA and 50 healthy age-matched controls. Serum levels of homocysteine (Hcy), uric acid (UA), and C-reactive protein (CRP) were measured. These levels positively correlated with the severity of MSA, based on both motor and non-motor symptoms. Several scales were used to rate the severity of MSA, including the Unified multiple system atrophy rating scale, Parkinson's disease sleep scale, Non-motor Symptoms Scale, the Schwab & England activities of daily living scale, Webster Scale, modified Hoehn and Yahr staging scale, and the Mini-Mental State Examination. Receiver operating characteristic (ROC) curves was applied to map the diagnostic accuracy of MSA against healthy subjects.

RESULTS

Compared with healthy subjects, we found that serum Hcy was higher, UA was lower, and CRP levels were unchanged in MSA patients. These findings were especially prominent in male patients. No significant differences of serum Hcy and UA were observed between patients of MSA and PD. Interestingly, there was a significant correlation between Hcy levels and MSA severity such as movement dysfunction, declined cognition, and cardiovascular symptoms. Additionally, the ROC curve for the combination of Hcy and UA (AUC 0.736) showed potential diagnostic value in discriminating MSA from healthy subjects.

CONCLUSION

Our findings suggest that the inflammatory mediators Hcy and UA may play important roles in the pathogenesis of MSA. The measurement of serum Hcy and UA levels could then be a useful tool to accurately distinguish MSA from healthy subjects.