Clinical Profile of Chinese Long-Term Parkinson's Disease Survivors With 10 Years of Disease Duration and Beyond

Prediction of Quality of Life in Patients With Parkinson’s Disease With and Without Excessive Daytime Sleepiness: A Longitudinal Study

Objective

There is a lack of longitudinal studies that directly compare the quality of life (QoL) and investigate the impact of clinical factors on QoL across different excessive daytime sleepiness (EDS) statuses in Parkinson’s disease (PD); therefore, we aimed to compare QoL and reveal the potential heterogeneous predictors of QoL between patients with PD with and without EDS.

Methods

We collected clinical data among 306 patients with PD over 2 years. EDS was assessed by the Epworth Sleepiness Scale and QoL was measured with the 39-item Parkinson’s Disease Questionnaire.

Results

We found that at both baseline and follow-up, patients with PD with EDS had poorer QoL and suffered more non-motor symptoms including depression and clinical probable rapid eye movement sleep behavior disorder (cpRBD). The generalized linear mixed model analysis indicated that the major predictors of QoL in PD with EDS were the akinetic-rigid type, disease duration, and total levodopa equivalent dose, while in PD without EDS, the primary determinants of QoL were Hoehn and Yahr, Mini-Mental State Examination (MMSE), and cpRBD.

Conclusion

Patients with PD with EDS presented with poorer QoL. Besides, the baseline predictors of future QoL differed between patients with PD with and without EDS. These findings remind clinicians to target specific clinical factors when attempting to improve QoL among patients with PD.

Monoamine Oxidase-B Inhibitors for the Treatment of Parkinson's Disease: Past, Present, and Future

Monoamine oxidase-B (MAO-B) inhibitors are commonly used for the symptomatic treatment of Parkinson’s disease (PD). MAO-B inhibitor monotherapy has been shown to be effective and safe for the treatment of early-stage PD, while MAO-B inhibitors as adjuvant drugs have been widely applied for the treatment of the advanced stages of the illness. MAO-B inhibitors can effectively improve patients’ motor and non-motor symptoms, reduce “OFF” time, and may potentially prevent/delay disease progression. In this review, we discuss the effects of MAO-B inhibitors on motor and non-motor symptoms in PD patients, their mechanism of action, and the future development of MAO-B inhibitor therapy.

SARS-CoV-2 Proteins Interact with Alpha Synuclein and Induce Lewy Body-like Pathology In Vitro

Growing cases of patients reported have shown a potential relationship between (severe acute respiratory syndrome coronavirus 2) SARS-CoV-2 infection and Parkinson’s disease (PD). However, it is unclear whether there is a molecular link between these two diseases. Alpha-synuclein (α-Syn), an aggregation-prone protein, is considered a crucial factor in PD pathology. In this study, bioinformatics analysis confirmed favorable binding affinity between α-Syn and SARS-CoV-2 spike (S) protein and nucleocapsid (N) protein, and direct interactions were further verified in HEK293 cells. The expression of α-Syn was upregulated and its aggregation was accelerated by S protein and N protein. It was noticed that SARS-CoV-2 proteins caused Lewy-like pathology in the presence of α-Syn overexpression. By confirming that SARS-CoV-2 proteins directly interact with α-Syn, our study offered new insights into the mechanism underlying the development of PD on the background of COVID-19.

Prevalence of freezing of gait in Parkinson's disease: a systematic review and meta-analysis

BACKGROUND

Freezing of gait (FOG) is considered one of the most disturbing and least understood symptoms in Parkinson's disease (PD). The reported prevalence rates of FOG in PD vary widely, ranging from 5 to 85.9%.

OBJECTIVE

We conducted a systematic review and meta-analysis to provide a reliable estimate of the average point prevalence of FOG in PD, and we further investigated the study characteristics that might have influenced the estimate.

METHODS

We searched different databases to identify studies that report the prevalence of FOG in PD or include relevant raw data for further calculation. The last inclusion date was February 20, 2020. The modified Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool was used for the quality assessment, and articles that met the predefined criteria were included in the quantitative analysis.

RESULTS

Sixty-six studies were selected from 3392 references. A weighted prevalence of 50.6% in 9072 PD patients experienced FOG based on the special questionnaires (the FOG-Q and NFOG-Q), which was about twice as high as that assessed by the specific items of the clinical rating scales (UPDRS item2.14 and MDS-UPDRS item3.11) (23.2%) or simple clinical questions (25.4%). The weighted prevalence was 37.9% for early stage (≤ 5 years) and 64.6% for advanced stage (≥ 9 years). Moreover, a higher prevalence was calculated from the population-based studies than that in multicenter and single-center studies (47.3% vs. 33.5% and 37.1%, respectively).

CONCLUSION

The result from this systematic review confirms that FOG is very common in PD and its prevalence is usually underestimated in hospital settings. Importantly, a more accurate assessment of FOG in future clinical researches would involve the use of special FOG scale rather than a single item on a scale or a general clinical inquiry.

P2X4R Overexpression Upregulates Interleukin-6 and Exacerbates 6-OHDA-Induced Dopaminergic Degeneration in a Rat Model of PD

The pathogenesis of Parkinson’s disease (PD) remains elusive. Current thinking suggests that the activation of microglia and the subsequent release of inflammatory factors, including interleukin-6 (IL-6), are involved in the pathogenesis of PD. P2X4 receptor (P2X4R) is a member of the P2X superfamily of ion channels activated by ATP. To study the possible effect of the ATP-P2X4R signal axis on IL-6 in PD, lentivirus carrying the P2X4R-overexpression gene or empty vector was injected into the substantia nigra (SN) of rats, followed by treatment of 6-hydroxydopamine (6-OHDA) or saline 1 week later. The research found the relative expression of P2X4R in the 6-OHDA-induced PD rat models was notably higher than that in the normal. And P2X4R overexpression could upregulate the expression of IL-6, reduce the amount of dopaminergic (DA) neurons in the SN of PD rats, suggesting that P2X4R may mediate the production of IL-6 to damage DA neurons in the SN. Our data revealed the important role of P2X4R in modulating IL-6, which leads to neuroinflammation involved in PD pathogenesis.

Effectiveness of Acupuncture in the Treatment of Parkinson's Disease: An Overview of Systematic Reviews

Background: The effects of acupuncture on Parkinson's disease (PD) outcomes remain unclear. The aim of this overview was to comprehensively evaluate the methodological quality and applicability of the results of systematic reviews (SRs)/meta-analyses (MAs) that examined the use of acupuncture to treat PD. Methods: Eight databases were searched to retrieve SRs/MAs on the use of acupuncture for the treatment of PD. Two reviewers independently screened and extracted the data using the Assessing the Methodological Quality of Systematic Reviews 2 (AMSTAR-2) checklist to evaluate the methodological quality and using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) criteria to assess the evidence quality of the included reviews. Results: A total of 11 SRs/MAs were included. According to the AMSTAR-2 checklist results, all included SRs/MAs were rated as very-low-quality studies. The GRADE criteria revealed 20 studies with very-low-quality evidence, 9 with low-quality evidence, 3 with moderate-quality evidence, and 0 with high-quality evidence. Descriptive analysis showed that acupuncture appears to be a clinically effective and safe treatment for PD. Conclusions: The use of acupuncture for the treatment of PD may be clinically effective and safe. This conclusion must be interpreted cautiously due to the generally low methodological quality and low quality of evidence of the included studies.

Lee Silverman Voice Treatment for dysarthria in patients with Parkinson's disease: a systematic review and meta-analysis

Approximately 89% of patients with Parkinson's disease (PD) suffer from dysarthria. Lee Silverman Voice Treatment (LSVT), a behavioral therapy, aims to improve speech and voice functions. The objective was to assess the effectiveness of LSVT compared with other/no speech interventions for dysarthria in patients with PD. Electronic databases, including PubMed, Embase and the Cochrane Library, were searched. The publication date of all included studies was before 6 March 2020. Only randomized controlled trials (RCTs) that evaluated the LSVT intervention compared with other/no speech intervention were considered. The data obtained from the included studies were described and the mean differences were calculated. Eight RCTs were included in this meta-analysis comparing LSVT with other/no speech interventions. In the comparison of LSVT versus no intervention, vocal intensity for sustained 'Ah' phonation, reading the 'Rainbow passage', monologue and describing a picture increased by 8.87, 4.34, 3.25 and 3.31 dB, respectively, after 1 month of therapy. Compared with the respiratory therapy group, the LSVT group also showed significant improvement in vocal intensity for sustained 'Ah' phonation, reading the 'Rainbow passage' and monologue immediately after treatment (13.39, 6.66 and 3.19 dB). Positive improvement still existed after 24 months. There was no difference in the therapeutic effect between face-to-face and online LSVT. The effectiveness of LSVT for dysarthria in patients with PD was verified in these trials. However, future RCTs with sufficient participants are essential to evaluate the effectiveness of LSVT for dysarthria.

Contra-Directional Expression of Plasma Superoxide Dismutase with Lipoprotein Cholesterol and High-Sensitivity C-reactive Protein as Important Markers of Parkinson's Disease Severity

Aim: Oxidative stress and inflammation play critical roles in the neuropathogenesis of PD. We aimed to evaluate oxidative stress and inflammation status by measuring serum superoxide dismutase (SOD) with lipoprotein cholesterol and high-sensitivity C-reactive protein (hsCRP) respectively in PD patients, and explore their correlation with the disease severity.

Methods: We performed a cross-sectional study that included 204 PD patients and 204 age-matched healthy controls (HCs). Plasma levels of SOD, hsCRP, total cholesterol, high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) were measured. A series of neuropsychological assessments were performed to rate the severity of PD.

Results: The plasma levels of SOD (135.7 ± 20.14 vs. 147.2 ± 24.34, P < 0.0001), total cholesterol, HDL-C and LDL-C in PD were significantly lower than those in HCs; the hsCRP level was remarkably increased in PD compared to HC (2.766 ± 3.242 vs. 1.637 ± 1.597, P < 0.0001). The plasma SOD was negatively correlated with the hsCRP, while positively correlated with total cholesterol, HDL-C, and LDL-C in PD patients. The plasma SOD were negatively correlated with H&Y, total UPDRS, UPDRS (I), UPDRS (II), and UPDRS (III) scores, but positively correlated with MoCA and MMSE scores. Besides, hsCRP was negatively correlated with MoCA; while total cholesterol, HDL-C and LDL-C were positively correlated with the MoCA, respectively.

Conclusion: Our findings suggest that lower SOD along with cholesterol, HDL-C and LDL-C, and higher hsCRP levels might be important markers to assess the PD severity. A better understanding of SOD and hsCRP may yield insights into the pathogenesis of PD.

Injection of α-syn-98 Aggregates Into the Brain Triggers α-Synuclein Pathology and an Inflammatory Response

Pathological aggregation of α-synuclein (α-syn) is a major component of Lewy bodies (LB), which play a central role in pathogenesis of Parkinson’s disease (PD). Differential expression of α-syn isoforms has been shown in PD. Isoform α-syn-98 is generated by excision of exon-3 and exon-5 of the α-syn gene. In contrast to the canonical full-length α-syn isoform (α-syn140), little is known about the function of the α-syn-98 isoform. In the present study, to identify the potential role of α-syn-98 protein in PD, we examined the effects of exogenous recombinant insoluble α-syn-98 aggregates on α-syn pathology and inflammatory responses in the midbrain. After injection of α-syn-98 aggregates into the substantia nigra (SN), mice exhibited motor dysfunction accompanied by nigral dopaminergic neuron loss. In addition, α-syn-98 aggregates injection resulted in a significant increase in phosphorylation of endogenous α-syn. Accumulations of α-syn were co-localized with p62 and ubiquitin, which suggests α-syn-98 aggregates-induced pathology exhibits properties similar to human LB. Many glial cells were activated after α-syn-98 aggregates injection. In addition, expression of NF-κB, interleukin 6 (IL6), and tumor necrosis factor-α (TNF-α) and levels of oxidative stress increased after α-syn-98 aggregates injection. Our results suggest that α-syn-98 may play a crucial role in the pathogenesis of PD.

Measurement of serum cystatin C: A valuable tool for evaluating dyskinesia in Parkinson's disease

Although cystatin C (Cys C) has been implicated in the pathophysiology of Parkinson's disease (PD), whether it can be used as a tool for evaluating dyskinesia is unknown. In the present study, the association of Cys C with dyskinesia in PD patients was investigated. Fasting serum Cys C levels were measured from 120 PD patients and 156 healthy controls. Demographic information was collected for all patients. In addition, levodopa (L-dopa)-equivalent dose, Unified Parkinson's Disease Rating Scale (UPDRS) score, Hoehn and Yahr (H&Y) stage, and dyskinesia were assessed in PD patients. Receiver operating characteristic (ROC) curves were adopted to assess the evaluating accuracy of Cys C levels for distinguishing dyskinesia in PD patients. Patients with PD exhibited significantly higher serum Cys C levels compared with heathy controls. Dyskinesia was observed in 32 patients (26.7%). Multiple logistic regression showed serum Cys C levels (odds ratio, OR 12.93; 95% confidence interval, CI 1.08-54.23; p = 0.043), duration of disease (OR 1.03, 95% CI 1.01-1.05, p = 0.001) and UPDRS II score (OR 1.07, 95% CI 1.01-1.14, p = 0.019) were independently associated with dyskinesia. The ROC curve for the Cys C levels yielded a valuable accuracy for distinguishing dyskinesia in PD patients. Serum Cys C levels were independently associated with dyskinesia and may be a valuable screening tool for differentiating dyskinesia in PD patients. Although the pathophysiological mechanism of PD is complicated, the results from our study provide a better understanding of the association between Cys C and dyskinesia in PD patients and may yield insights into the pathogenesis of PD.

Nitrated alpha-synuclein in minor salivary gland biopsies in Parkinson's disease

Alpha-synuclein (α-SYN) is found in peripheral autonomic neuronal network apart from brain in Parkinson's disease (PD). Nitrated α-SYN is an undesirable modification associated with oxidative and nitrative damage and has been found extensively in brain, gastrointestinal(GI) tract and blood cells in PD. We aim to investigate the presence of nitrated α-SYN in minor salivary gland biopsy in PD. Patients with PD and age-matched controls underwent minor salivary gland biopsy. Motor impairment was assessed by Hoehn-Yahr (H-Y) stage and Unified Parkinson's Disease Rating Scale (UPDRS) Part III in off-state. 11C-methyl-N-2b-carbomethoxy-3b-(4-fluorophenyl) tropane (11C-CFT) DAT-PET scan was performed in all subjects. Immunohistochemical staining for nitrated α-SYN was performed in the minor salivary gland tissues. The minor salivary gland tissues of 8 PD cases and 7 controls with early stage (H-Y stage 1-2) were detected. All PD patients showed asymmetrical and reduction of ¹¹C-CFT uptake in the caudate, anterior and posterior putamen, while all control subjects showed normal DAT-PET scan. Positive nitrated α-SYN immunostaining was observed in all PD patients (8/8,100%) but not in control subjects (0/7). The results were consistent well with that of DAT-PET. These nitrated alpha-synuclein positive structures were mainly located in the periacinar stroma in PD patients. Our result suggests that nitrated α-SYN exists in the early stage and is probably a promising biomarker for PD. Minor salivary gland is an ideal site for α-SYN nitration detection. Despite of the small number of subjects, attention should be given to α-SYN nitration in PD and more investigations on nitrated α-SYN in different sites and large sample using should be explored in future.

Advances in the Research of Risk Factors and Prodromal Biomarkers of Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disease in the world. With the advent of an aging population and improving life expectancy worldwide, the number of PD patients is expected to increase, which may lead to an urgent need for effective preventive and diagnostic strategies for PD. Although there is increasing research regarding the pathogenesis of PD, there is limited knowledge regarding the prevention of PD. Moreover, the diagnosis of PD depends on clinical criteria, which require the occurrence of bradykinesia and at least one symptom of rest tremor or rigidity. However, converging evidence from clinical, genetic, neuropathological, and imaging studies suggests the initiation of PD-specific pathology prior to the initial presentation of these classical motor clinical features by years or decades. This latent stage of neurodegeneration in PD is a particularly important stage for effective neuroprotective therapies, which might retard the progression or prevent the onset of PD. Therefore, the exploration of risk factors and premotor biomarkers is not only crucial to the early diagnosis of PD but is also helpful in the development of effective neuroprotection and health care strategies for appropriate populations at risk for PD. In this review, we searched and summarized ∼249 researches and 31 reviews focusing on the risk factors and prodromal biomarkers of PD and published in MEDLINE.

Dopaminergic pathway and primary visual cortex are involved in the freezing of gait in Parkinson's disease: a PET-CT study

Background: Freezing of gait (FOG) could be partly alleviated by dopaminergic drugs but the mechanism still needs to be elucidated. The purpose of this study is to explore the mechanisms of FOG by vesicular monoamine transporter VMAT2 distribution with the ¹⁸F-AV133 tracer and 18-fludeoxyglucose positron emission tomography-computed tomography (¹⁸F-FDG PET-CT). Methods: Clinical material and PET-CT data were collected from 20 patients with FOG and 147 patients without FOG from November 1, 2017 to October 31, 2018. Brain scans of all participants were acquired over an approximately 20-min period, 120 min after injection of approximately 250 MBq ¹⁸F-AV133. The mean uptake ratios of different regions were identified by NeuroQ software of ¹⁸F-FDG PET-CT. Data analysis included variance, chi-square analysis, covariance analysis, and logistic regression. Results: Our data showed that patients with FOG were provided with greater doses of dopaminergic drugs (p<0.05). The frequency of FOG was 11.98% and increased as Parkinson's disease progressed. FOG was more common in the elderly and strongly associated with the duration. Cognitive impairments were obvious, assessed by Mini-Mental State Examination and Montreal Cognitive Assessment (p<0.05). The VMAT2 distribution with ¹⁸F-AV133 was decreased significantly in the caudate nucleus and lentiform nucleus while the metabolism of these areas was elevated, determined by ¹⁸F-FDG PET-CT (p<0.05). The metabolism of the primary visual cortex decreased obviously in patients with FOG compared with those without FOG (p<0.05). Conclusion: FOG mainly occurred in the advanced stage, and was strongly associated with the duration and larger dose of dopaminergic drugs. The dopamine level of the nigrostriatal system decreased significantly and the uptake ratios of the primary visual cortex dropped obviously in the FOG group compared with the non-FOG group. Our study suggests that both the dopaminergic pathway and the primary visual cortex are involved in the pathogenesis of FOG.