Epidemiology of Parkinson's disease

The epidemiology of Parkinson's disease

The epidemiology of Parkinson's disease shows marked variations in time, geography, ethnicity, age, and sex. Internationally, prevalence has increased over and above demographic changes. There are several potential reasons for this increase, including the decline in other competing causes of death. Whether incidence is increasing, especially in women or in many low-income and middle-income countries where there is a shortage of high-quality data, is less certain. Parkinson's disease is more common in older people and men, and a variety of environmental factors have been suggested to explain why, including exposure to neurotoxic agents. Within countries, there appear to be ethnic differences in disease risk, although these differences might reflect differential access to health care. The cause of Parkinson's disease is multifactorial, and involves genetic and environmental factors. Both risk factors (eg, pesticides) and protective factors (eg, physical activity and tendency to smoke) have been postulated to have a role in Parkinson's disease, although elucidating causality is complicated by the long prodromal period. Following the establishment of public health strategies to prevent cardiovascular diseases and some cancers, chronic neurodegenerative diseases such as Parkinson's disease and dementia are gaining a deserved higher priority. Multipronged prevention strategies are required that tackle population-based primary prevention, high-risk targeted secondary prevention, and Parkinson's disease-modifying therapies for tertiary prevention. Future international collaborations will be required to triangulate evidence from basic, applied, and epidemiological research, thereby enhancing the understanding and prevention of Parkinson's disease at a global level.

Effect of best practice advisory on the administration of contraindicated medications to hospitalized patients with Parkinson's disease and related disorders

Objective

To determine the effect of a Best Practice Advisory (BPA) on the ordering and administration of contraindicated dopamine blocking agents (DBA) to hospitalized patients with Parkinson's disease (PD) and related disorders.

Background

Patients with PD are more likely to require hospitalization and are at increased risk of complications. Administration of contraindicated DBA contributes to worsened outcomes in this patient population. Electronic medical record (EMR) warnings (also referred to as BPA) have been proposed as a way to prevent the administration of contraindicated medications.

Methods

A BPA was launched in January 2020 within the University of Rochester EMR system, which alerts the provider when a contraindicated DBA is ordered in hospitalized patients with PD and related disorders. Patients with PD and related disorders hospitalized at two hospitals affiliated to the University of Rochester during a time period before (t1: 1/1/2019-1/1/2020) and after (t2: 1/8/2020-1/8/2021) the implementation of the BPA were included in this study. Epic SliderDicer was used to collect the data from the University of Rochester EMR. The number of patients who had contraindicated DBA orders and administrations in both time periods, and the number of patients who had the BPA triggered during t2 were obtained. We compared the results before and after the implementation of the BPA.

Results

306 patients with PD and related disorders were hospitalized during t1 and 273 during t2. There was significantly less percentage of patients who had contraindicated DBA orders (41.5% in t1 vs. 17.6% in t2) and patients who had contraindicated DBA administrations (16% in t1 vs. 8.8% in t2) during t2 (p < 0.05 for both comparisons). There was no significant difference between the percentage of patients who had contraindicated DBA orders in t1 and patients with attempted orders (BPA triggered) in t2 (p = 0.27).

Conclusion

The results of this study increase the evidence of the potential benefit of EMR warnings for the optimization of inpatient medication management in patients with PD and related disorders. In particular, our results suggest that EMR warnings help reduce the administration of contraindicated medications, which is a known contributing factor for hospital complications in this patient population.

Chronic effects of different exercise types on brain activity in healthy older adults and those with Parkinson’s disease: A systematic review

Objective: This study aimed to compare the regulation of brain activity by different kinds of long-term exercises (Tai Chi, treadmill training, and dancing) in healthy older adults and those with PD.

Methods: From January 2000 to October 2021, the electronic databases PubMed, Web of Science, and Scopus were searched. All articles were screened throughout the inclusion and exclusion criteria, which was followed by PICOS criteria. Finally, all articles were systematically reviewed with analyses.

Results: 29 studies were identified for this review, 24 of which were finally included in a group of healthy older adults, and five of which in a group of people with PD. All studies showed that significant changes were showed on people with PD and healthy older adults’ brain activity after three terms of the exercises we chose. An inverse change trend on the functional connectivity in people with PD was observed after treadmill training, whereas increased brain activity, cognitive function, memory, and emotion were noticed in healthy older adults.

Conclusion: Our findings suggest that different patterns of brain activity were also observed between healthy older adults and people with PD after treadmill training. However, more robust evidence and comprehensive studies are needed to determine if there is a difference between healthy older adults and people with PD.

Structural and Functional Impact of Damaging Nonsynonymous Single Nucleotide Polymorphisms (nsSNPs) on Human VPS35 Protein Using Computational Approaches

Parkinson's disease is the second most common progressive neurodegenerative movement disorder. Mutations in retromer complex subunit and VPS35 represent the second most common cause of late-onset familial Parkinson's disease. The mutation in VPS35 can disrupt the normal protein functions resulting in Parkinson's disease. The aim of this study was the identification of deleterious missense Single Nucleotide Polymorphisms (nsSNPs) and their structural and functional impact on the VPS35 protein. In this study, several insilico tools were used to identify deleterious and disease-associated nsSNPs. 3D structure of VPS35 protein was constructed through MODELLER 9.2, normalized using FOLDX, and evaluated through RAMPAGE and ERRAT whereas, FOLDX was used for mutagenesis. 25 ligands were obtained from literature and docked using PyRx 0.8 software. Based on the binding affinity, five ligands i.e., PG4, MSE, GOL, EDO, and CAF were further analyzed. Molecular Dynamic simulation analysis was performed using GROMACS 5.1.4, where temperature, pressure, density, RMSD, RMSF, Rg, and SASA graphs were analyzed. The results showed that the mutations Y67H, R524W, and D620N had a structural and functional impact on the VPS35 protein. The current findings will help in appropriate drug design against the disease caused by these mutations in a large population using in-vitro study.

A review of dementia, focusing on the distinct roles of viral protein corona and MMP9 in dementia: Potential pharmacotherapeutic priorities

Dementia, in particular, is a defining feature of Alzheimer's and Parkinson's diseases. Because of the combination of motor and cognitive impairments, Parkinson's disease dementia (PDD) has a greater impact on affected people than Alzheimer's disease dementia (ADD) and others. If one family member develops dementia, the other members will suffer greatly in terms of social and occupational functioning. Currently, no relevant treatment is available based on an examination of the absolute pathophysiology of dementia. As a result, our objective of current review encouraged to look for dementia pharmacotherapy based on their pathogenesis. We systematically searched electronic databases such as PubMed, Scopus, and ESCI for information on the pathophysiology of demetia, as well as their treatment with allopathic and herbal medications. By modulating intermediate proteins, oxidative stress, viral protein corona, and MMP9 are etiological factors that cause dementia. The pathophysiology of ADD was described by two hypotheses: the amyloid cascade hypothesis and the tau and tangle hypothesis. ADD is caused by an increase in amyloid-beta (Aβ) and neurofibrillary tangles in the cerebrum. The viral protein corona (VPC) is more contagious and helps to form amyloid-beta (Aβ) plaques and neurofibrillary tangles in the cerebrum. Thioredoxin interacting protein (TXNIP) inside the BBB encourages Aβ to become more engaged. PDD is caused by decreased or absent dopamine secretion from nerve cells in the substantia nigra, as well as PRKN gene deletion/duplication mutations, and shift in the PRKN-PACRG organisation, all of which are linked to ageing. This article discussed the pathophysiology of dementia, as well as a list of herbal medications that can easily cross the BBB and have a therapeutic effect on dementia.

Immunotherapeutic interventions in Parkinson's disease: Focus on α-Synuclein

Parkinson's disease (PD) is a neurodegenerative disorder characterized classically by motor manifestations. However, nonmotor symptoms appear early in the course of the disease progression, making both diagnosis and treatment difficult. The pathology of PD is complicated by the accumulation and aggregation of misfolded proteins in intracellular cytoplasmic inclusions called Lewy bodies (LBs). The main toxic component of LBs is the protein α-Synuclein which plays a pivotal role in PD pathogenesis. α-Synuclein can propagate from cell-to-cell exhibiting prion-like properties and spread PD pathology throughout the central nervous system. Immunotherapeutic interventions in PD, both active and passive immunization, have targeted α-Synuclein in both experimental models and clinical trials. In addition, targeting the hyperactive inflammation in PD also holds promise in designing potential immunotherapeutics. The inflammatory and proteotoxic pathways are interlinked and contribute immensely to the disease pathology. In this chapter, we critically review the targets of immunotherapeutic interventions in PD, focusing on the pathogenetic mechanisms of PD, particularly neuroinflammation and α-Synuclein misfolding, aggregation, and propagation. We thoroughly summarized the various immunotherapeutic strategies designed to treat PD-in vitro, in vivo, and clinical trials. The development of these targeted immunotherapies could open a new avenue in the treatment of patients with PD.

Prevalence of parkinsonism and Parkinson disease in urban and rural populations from Latin America: A community based study

Background

Age and gender specific prevalence rates for parkinsonism and Parkinson's disease (PD) are important to guide research, clinical practice, and public health planning; however, prevalence estimates in Latin America (LatAm) are limited. We aimed to estimate the prevalence of parkinsonism and PD and examine related risk factors in a cohort of elderly individuals from Latin America (LatAm).

Methods

Data from 11,613 adults (65+ years) who participated in a baseline assessment of the 10/66 study and lived in six LatAm countries were analyzed to estimate parkinsonism and PD prevalence. Crude and age-adjusted prevalence were determined by sex and country. Diagnosis of PD was established using the UK Parkinson's Disease Society Brain Bank's clinical criteria.

Findings

In this cohort, the prevalence of parkinsonism was 8.0% (95% CI 7.6%-8.5%), and the prevalence of PD was 2.0% (95% CI 1.7%-2.3%). PD prevalence increased with age from 1.0 to 3.5 (65-69vs. 80 years or older, p < 0.001). Age-adjusted prevalence rates were lower for women than for men. No significant differences were found across countries, except for lower prevalence in urban areas of Peru. PD was positively associated with depression (adjusted prevalence ratio [aPR] 2.06, 95% CI 1.40-3.01, I ² = 56.0%), dementia (aPR 1.57, 95% CI 1.07- 2.32, I ² = 0.0%) and educational level (aPR 1.14, 95% CI 1.01- 1.29, I ² = 58.6%).

Interpretation

The reported prevalence of PD in LatAm is similar to reports from high-income countries (HIC). A significant proportion of cases with PD did not have a previous diagnosis, nor did they seek any medical or neurological attention. These findings underscore the need to improve public health programs for populations currently undergoing rapid demographic aging and epidemiological transition.

Funding

The funding source had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Clinical and Genetic Analysis of Costa Rican Patients With Parkinson's Disease

Background: Most research in genomics of Parkinson's disease (PD) has been done in subjects of European ancestry, leading to sampling bias and leaving Latin American populations underrepresented. We sought to clinically characterize PD patients of Costa Rican origin and to sequence familial PD and atypical parkinsonism-associated genes in cases and controls.

Methods: We enrolled 118 PD patients with 97 unrelated controls. Collected information included demographics, exposure to risk and protective factors, and motor and cognitive assessments. We sequenced coding and untranslated regions in familial PD and atypical parkinsonism-associated genes including GBA, SNCA, VPS35, LRRK2, GCH1, PRKN, PINK1, DJ-1, VPS13C, and ATP13A2.

Results: Mean age of PD probands was 62.12 ± 13.51 years; 57.6% were male. The frequency of risk and protective factors averaged ~45%. Physical activity significantly correlated with better motor performance despite years of disease. Increased years of education were significantly associated with better cognitive function, whereas hallucinations, falls, mood disorders, and coffee consumption correlated with worse cognitive performance. We did not identify an association between tested genes and PD or any damaging homozygous or compound heterozygous variants. Rare variants in LRRK2 were nominally associated with PD; six were located between amino acids p.1620 and 1623 in the C-terminal-of-ROC (COR) domain of Lrrk2. Non-synonymous GBA variants (p.T369M, p.N370S, and p.L444P) were identified in three healthy individuals. One PD patient carried a pathogenic GCH1 variant, p.K224R.

Discussion: This is the first study that describes sociodemographics, risk factors, clinical presentation, and genetics of Costa Rican patients with PD, adding information to genomics research in a Latino population.

[Sleep disorders in synucleinopathy]

The article highlights the current state of the problem of sleep disorders in various neurodegenerative diseases. The clinical picture and diagnosis of these disorders are described in detail. Separately, the emphasis is made on the mechanisms underlying development of these disorders and their features in various forms of synucleinopathies. The mediator and physiological changes that underlie sleep disorders in various nosological units of synucleinopathies are discussed in detail. The current attitude to certain sleep disorders as predictors of neurodegenerative diseases is evaluated. The role of the glymphatic system in the development of these disorders is considered. Also, modern therapeutic strategies for sleep disorders in neurodegenerative diseases are discussed.

The Rostock International Parkinson's Disease (ROPAD) Study: Protocol and Initial Findings

Background

Genetic stratification of Parkinson's disease (PD) patients facilitates gene‐tailored research studies and clinical trials. The objective of this study was to describe the design of and the initial data from the Rostock International Parkinson's Disease (ROPAD) study, an epidemiological observational study aiming to genetically characterize ~10,000 participants.

Methods

Recruitment criteria included (1) clinical diagnosis of PD, (2) relative of participant with a reportable LRRK2 variant, or (3) North African Berber or Ashkenazi Jew. DNA analysis involved up to 3 successive steps: (1) variant (LRRK2) and gene (GBA) screening, (2) panel sequencing of 68 PD‐linked genes, and (3) genome sequencing.

Results

Initial data based on the first 1360 participants indicated that the ROPAD enrollment strategy revealed a genetic diagnostic yield of ~14% among a PD cohort from tertiary referral centers.

Conclusions

The ROPAD screening protocol is feasible for high‐throughput genetic characterization of PD participants and subsequent prioritization for gene‐focused research efforts and clinical trials. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Methods for detecting toxic α-synuclein species as a biomarker for Parkinson's disease

Parkinson's disease (PD) is the most common neurodegenerative movement disorder and is characterized by the accumulation of α-synuclein (α-syn) into insoluble aggregates known as Lewy bodies and Lewy neurites in the brain. However, prior to the formation of these large aggregates, α-syn forms oligomers and small fibrils, which are believed to be the pathogenic species leading to the death of neurons in the substantia nigra in disease. The majority of aggregated α-syn is phosphorylated, and it is thought that this post-translational modification may be critical in disease pathogenesis. Thus, early detection of the toxic forms of α-syn may provide a window of opportunity for an intervention to halt or slow the progression of neurodegeneration in PD. Expression of α-syn is not restricted to the central nervous system and the protein can be found elsewhere, including bodily fluids and peripheral tissues. This review will examine current methods for detecting toxic forms of α-syn in accessible biospecimens and outline emerging techniques that may provide reliable identification of biomarkers for PD.

Chemical composition and health properties of coffee and coffee by-products

Coffee can be an ally in the fight against diseases such as type 2 diabetes, cancer, hepatic injury, cirrhosis, depression, suicidal behavior, and neurological and cardiovascular disorders. The properties of coffee also favor gastrointestinal tract and gut microbiota establishment. Coffee bioactive components include phenolic compounds (chlorogenic acids, cafestol and kahweol), alkaloids (caffeine and trigonelin), diterpenes (cafestol and kahweol) and other secondary metabolites. The image of coffee as a super functional food has helped to increase coffee consumption across the globe. This chapter addresses the main health promotion mechanisms associated with coffee consumption. Related topics on coffee production chain, world consumption and reuse of coffee by-products in the production of high-value-adding molecules with potential applications in the food industry are addressed and discussed.

Impact of Safety Warning on Domperidone Prescribing for Geriatric Patients in South Korea: Analysis of National Insurance Claim Data

Domperidone is a dopamine antagonist used for the symptomatic management of nausea and vomiting. Many countries banned or add a black box warning due to an increased risk of serious adverse cardiac effects. In 2014, the Korea Ministry of Food and Drug Safety also released a safety warning to carefully consider adverse cardiac effects when prescribing domperidone. Therefore, we conducted this study to analyze the impact of the safety warning on domperidone prescribing. This study included patients 65 years or older who used national health insurance services in the years 2011 and 2016, using the national patient sample dataset in South Korea. We analyzed the characteristics of domperidone prescribing and compared on pre- and post-safety warning. Prescribing frequency of domperidone was significantly reduced from 603,962 cases in 2011 to 24,623 cases in 2016. In 2011, 53,272 (8.8%) prescriptions were for greater than 30 mg/day, whereas only 200 (0.8%) prescriptions were in 2016. The number of patients with one or more comorbidities and electrocardiogram monitoring showed positive changes after the safety warning. In conclusion, after the 2014 safety letter was issued, domperidone was more safely prescribed in various aspects in elderly patients, including frequency of prescribing, maximum daily dose, and duration of continuous prescription.

Physiological complexity of gait between regular and non-exercisers with Parkinson's disease

BACKGROUND

Physiological complexity represents overall health of a system and its underlying capacity to adapt to stresses. The primary purpose of this study was to determine if physiological complexity of gait both ON and OFF anti-Parkinson medication differed between regular and non-exercisers with Parkinson's disease.

METHODS

Twenty participants with idiopathic Parkinson's disease were enrolled in this cross-sectional study (regular exercisers n = 10, non-exercisers n = 10). Two data collection sessions were completed during a single visit, first after a 12-hour overnight withdrawal from anti-Parkinson medications (OFF), and again one-hour after taking anti-Parkinson medications (ON). During each session participants completed a 2-minute walking task at their preferred pace while wearing wireless inertial measurement units on each lower extremity segment (thigh, shank, foot). Multivariate multiscale entropy was calculated from the tri-axial accelerometer signals and converted to a complexity index for analysis.

FINDINGS

Regular exercisers demonstrated significantly higher complexity indices ON and OFF anti-Parkinson medications compared to non-exercisers (ON F = 3.84 P = 0.02; OFF F = 3.61, P < 0.03). Regular exercisers did not significantly differ in complexity between OFF and ON states (most affected leg F = 0.15 P = 0.71; least affected leg F = 0.30 P = 0.60), but non-exercisers demonstrated significantly decreased complexity in the least affected leg OFF anti-Parkinson medications (F = 5.17 P < 0.04).

INTERPRETATION

Enhanced gait complexity in the regular exercisers may indicate that ongoing exercise is a key ingredient contributing to health in persons with Parkinson's disease. Exercising on a regular basis with Parkinson's disease may augment one's ability to adapt to barriers encountered during gait regardless of medication state.

Chronic Neurodegenerative Illnesses and Epilepsy in Danish Adventists and Baptists: A Nationwide Cohort Study

BACKGROUND

Limited knowledge of the influence of lifestyle risk factors and religious living on chronic neurological diseases exists. Seventh-day Adventists (SDA) do not consume tobacco, alcohol, or pork, and many adhere to lacto-ovo-vegetarian diet, and Baptists discourage excessive use of alcohol and tobacco.

OBJECTIVE

We investigated whether the incidence of four common chronic neurological illnesses: dementia, Alzheimer's disease, Parkinson's disease, and epilepsy in a large cohort of Danish Adventists and Baptists was different compared to the general Danish population. Three of the illnesses are neurodegenerative, whereas epilepsy can occur at any age.

METHODS

We compared hospital admission rates for some major neurological diseases among members of the Danish Religious Societies Health Study comprising 6,532 SDA and 3,720 Baptists with the general Danish population. Standardized incidence ratios (SIR) stratified by sex, age, and calendar time were calculated.

RESULTS

SIR of dementia or Alzheimer's disease was significantly decreased for members of both communities (SDA, 0.78; 95% CI, 0.67-#x2013;0.90 and Baptists, 0.59; 0.47-#x2013;0.73). The SIRs of Parkinson's disease and epilepsy were not significantly different compared to the general population.

CONCLUSIONS

We observe reduced incidence for dementia or Alzheimer's disease in a large cohort of members of two religious communities characterized by lifestyle recommendations. More studies are needed to disentangle the interaction between such lifestyle and other components of the religious belief system.

The Genetics of Parkinson Disease

The 200years of research efforts on Parkinson disease (PD) form the basis of our understanding of the second most common neurodegenerative disorder after Alzheimer disease. This journey has been marked by the revolutionary discovery of a neurotransmitter replacement therapy that provides a longer and healthier life to patients. Since 1997, the advances in the genetics of PD have expanded our understanding of this neurodegenerative disorder and they are opening up new ways to search for disease-modifying therapies. This chapter is a summary of the historical discoveries and latest progress in PD research.

Management Impact of Imaging Brain Vesicular Monoamine Transporter Type 2 in Clinically Uncertain Parkinsonian Syndrome with 18F-AV133 and PET

Idiopathic Parkinson disease is a common neurodegenerative disorder for which misdiagnosis occurs in up to 30% of patients after initial assessment and in 10%-15% even after long-term follow-up. Vesicular monoamine transporter type 2 (VMAT2) imaging with PET allows assessment of the integrity of the presynaptic dopaminergic pathway. We investigated the management impact of VMAT2 imaging in patients with clinically uncertain Parkinsonian syndromes. Methods: Forty-seven patients with clinically uncertain Parkinsonian syndromes (mean age ± SD, 56.9 ± 14.9 y; age range, 21-80 y) were referred from movement disorder specialists. All participants underwent a 20-min PET acquisition 2 h after injection of 250 MBq of ¹⁸F-AV-133, and the resulting images were quantitatively assessed. Clinical impact was recorded as high, moderate, or low based on diagnosis and management questionnaires completed by the referring specialists before and after release of the PET results. Management impact was high if there was a change in diagnostic category, moderate if there was a change in medication, and low if there was no change. Results: VMAT2 PET changed the diagnosis in 11 (23%) and medication in 25 (53%) participants. Management impact was high in 23%, moderate in 38%, and low in 39% of the participants. High diagnostic confidence increased from 11% of patients to 80% after the release of the scan results. Conclusion:¹⁸F-AV-133 had substantial management impact in patients with clinically uncertain Parkinsonian syndromes. VMAT2 imaging with ¹⁸F-AV133 might improve diagnosis, prognosis, and appropriate use of medication, translating into better patient outcomes.

Gastrointestinal Dysfunction and Neuropathologic Correlations in Parkinson Disease

INTRODUCTION

Recently, an increasing interest to nonmotor symptoms of Parkinson disease (PD) has shown. Gastrointestinal dysfunction is a prominent nonmotor manifestation of PD and precedes motor symptoms for several years. Neuropathologic studies show early accumulation of α-synuclein (α-SYN) in Lewy neurites and Lewy body in the enteric nervous system (ENS) and dorsal motor nucleus of the vagus in PD. Our study aims to investigate relationship between α-SYN deposition in ENS and gastrointestinal dysfunction in PD.

MATERIALS AND METHODS

We conducted a study in Neurology Department of Charles Nicolle Hospital of Tunis during 2 years (2013 to 2014) including PD patients. Clinical data were analyzed. Digestive endoscopy with biopsies of upper digestive tract (UDT) and immunohistochemistry study were performed.

RESULTS

Thirty patients (16♂/14♀) and 13 (7♂/6♀) controls were included. Average age was 65 years for patients and 63.5 years for controls. Gastrointestinal symptoms were the most frequent nonmotor symptoms occurring in 73%. Endoscopy showed motor dysfunction of upper digestive tract in 5 patients. Lesion load in α-SYN was significantly correlated with frequency and severity of gastrointestinal dysfunction and PD motor disability.

CONCLUSIONS

Gastrointestinal disturbances are frequent in PD. ENS's synucleinopathy could entirely explain pathophysiology of digestive dysfunction and is correlated with severity of gastrointestinal symptoms in PD. Biopsies may show α-SYN aggregates in immunoreactive Lewy neurites in the submucosal and myenteric plexus. Thus, endoscopic and immunohistochemical exploration of ENS may be a biomarker for Parkinson enteropathy and for PD overall.

Lower limb progressive resistance training improves leg strength but not gait speed or balance in Parkinson's disease: a systematic review and meta-analysis

The use of progressive resistance training (PRT) to improve gait and balance in people with Parkinson’s disease (PD) is an emerging area of interest. However, the main effects of PRT on lower limb functions such as gait, balance, and leg strength in people with PD remain unclear. Therefore, the aim of the meta-analysis is to evaluate the evidence surrounding the use of PRT to improve gait and balance in people with PD. Five electronic databases, from inception to December 2014, were searched to identify the relevant studies. Data extraction was performed by two independent reviewers and methodological quality was assessed using the PEDro scale. Standardized mean differences (SMD) and 95% confidence intervals (CIs) of fixed and random effects models were used to calculate the effect sizes between experimental and control groups and I² statistics were used to determine levels of heterogeneity. In total, seven studies were identified consisting of 172 participants (experimental n = 84; control n = 88). The pooled results showed a moderate but significant effect of PRT on leg strength (SMD 1.42, 95% CI 0.464–2.376); however, no significant effects were observed for gait speed (SMD 0.418, 95% CI −0.219 to 1.055). No significant effects were observed for balance measures included in this review. In conclusion, our results showed no discernable effect of PRT on gait and balance measures, although this is likely due to the lack of studies available. It may be suggested that PRT be performed in conjunction with balance or task-specific functional training to elicit greater lower limb functional benefits in people with PD.

Parkinson's disease and enhanced inflammatory response

Parkinson's disease (PD) is the first and second most prevalent motor and neurodegenerative disease, respectively. The clinical symptoms of PD result from a loss of midbrain dopaminergic (DA) neurons. However, the molecular cause of DA neuron loss remains elusive. Mounting evidence implicates enhanced inflammatory response in the development and progression of PD pathology. This review examines current research connecting PD and inflammatory response.

L-Dopa and Brain Serotonin System Dysfunction

L-dopa is used to treat the motor symptoms associated with Parkinson's disease, a neurodegenerative movement disorder characterized by a loss of dopamine neurons. L-dopa is the precursor to dopamine and crosses the blood-brain barrier to increase dopamine neurotransmission. This review will focus on the findings that dopamine produced from L-dopa is mediated in part by serotonin neurons. Direct evidence will be provided that increases in dopamine cause oxidative stress and damage serotonin neurons. Similarly, chronic L-dopa produces deficits in serotonin neurotransmission, including decreases in both serotonin cell bodies within the dorsal raphe and serotonin neurotransmitter concentrations in several forebrain regions. Since serotonin is involved in many important physiological processes including mood and cognition, L-dopa induced serotonin deficits may play a role in the side-effect symptoms observed in Parkinson's disease patients treated with L-dopa.

Progressive decline of glucocerebrosidase in aging and Parkinson's disease

The principal risk factor for developing most adult onset neurodegenerative diseases is aging, with incidence rising significantly after age 50. Despite research efforts, the causes of Parkinson's disease (PD) remain unknown. As neurons age, they show signs of diminished lysosomal and mitochondrial function, including increased oxidative stress and accumulation of misfolded proteins, and these changes become exacerbated PD. We show that activity of the lysosomal hydrolase glucocerebrosidase gradually diminishes with age in the substantia nigra and putamen of healthy controls. This reduction is comparable to glucocerebrosidase activity in GBA1-mutation carrier PD patients. These data, demonstrate for the first time that an age-dependent reduction in glucocerebrosidase activity may lower the threshold for developing PD.

δ-Opioid receptor activation reduces α-synuclein overexpression and oligomer formation induced by MPP(+) and/or hypoxia

Hypoxic/ischemic brain injury is a potential cause of Parkinson's disease (PD) with ɑ-synuclein playing a critical role in the pathophysiology. Since δ-opioid receptor (DOR) is neuroprotective against hypoxic/ischemic insults, we sought to determine if DOR regulates ɑ-synuclein under hypoxia and/or MPP(+) stress. We found that in HEK293 cells 1) MPP(+) in normoxia enhanced ɑ-synuclein expression and the formation of ɑ-synuclein oligomers thereby causing cytotoxic injury; 2) hypoxia at 1% O2 for 48h or at 0.5% O2 for 24h also induced ɑ-synuclein overexpression and its oligomer formation with cell injury; 3) however, hypoxia at 1% O2 for 24h, though increasing ɑ-synuclein expression, did not cause ɑ-synuclein oligomer formation and cell injury; 4) UFP-512 mediated DOR activation markedly attenuated the hypoxic cell injury and ɑ-synuclein overexpression, which was largely attenuated by DOR antagonism with naltrindole or siRNA "knock-down" of the DOR; and 5) DOR activation enhanced CREB phosphorylation and prevented the collapse of mitochondrial membrane potential (△ψm). These findings suggest that DOR activation attenuates MPP(+) or severe hypoxia induced ɑ-synuclein expression/aggregation via a CREB pathway.

Deep brain stimulation: are astrocytes a key driver behind the scene?

Despite its widespread use, the underlying mechanism of deep brain stimulation (DBS) remains unknown. Once thought to impart a "functional inactivation", there is now increasing evidence showing that DBS actually can both inhibit neurons and activate axons, generating a wide range of effects. This implies that the mechanisms that underlie DBS work not only locally but also at the network level. Therefore, not only may DBS induce membrane or synaptic plastic changes in neurons over a wide network, but it may also trigger cellular and molecular changes in other cells, especially astrocytes, where, together, the glial-neuronal interactions may explain effects that are not clearly rationalized by simple activation/inhibition theories alone. Recent studies suggest that (1) high-frequency stimulation (HFS) activates astrocytes and leads to the release of gliotransmitters that can regulate surrounding neurons at the synapse; (2) activated astrocytes modulate synaptic activity and increase axonal activation; (3) activated astrocytes can signal further astrocytes across large networks, contributing to observed network effects induced by DBS; (4) activated astrocytes can help explain the disparate effects of activation and inhibition induced by HFS at different sites; (5) astrocytes contribute to synaptic plasticity through long-term potentiation (LTP) and depression (LTD), possibly helping to mediate the long-term effects of DBS; and (6) DBS may increase delta-opioid receptor activity in astrcoytes to confer neuroprotection. Together, the plastic changes in these glial-neuronal interactions network-wide likely underlie the range of effects seen, from the variable temporal latencies to observed effect to global activation patterns. This article reviews recent research progress in the literature on how astrocytes play a key role in DBS efficacy.

Microstructural changes in the substantia nigra of asymptomatic agricultural workers

Parkinson's disease (PD) is marked by the loss of dopamine neurons in the substantia nigra (SN). Although the exact etiology is unknown, sporadic PD is hypothesized to be a result of genetic susceptibility interacting with environmental insult. Epidemiological studies suggest that pesticide exposure is linked to higher PD risk, but there are no studies demonstrating SN changes with chronic pesticide exposure in human subjects. Thus, high resolution T2-weighted magnetic resonance imaging (MRI) and diffusion tensor (DTI) images were obtained from 12 agricultural workers with chronic pesticide exposure, 12 controls, and 12 PD subjects. Neither controls nor pesticide-exposed subjects, had any parkinsonian symptoms. Exposure history to pesticides was assessed by a structured questionnaire. DTI measures in the SN, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD), were obtained for all subjects and compared among groups. Compared to controls, PD patients showed the expected significant changes in all DTI measurements in the SN. The pesticide-exposed subjects, compared to controls, had significantly lower FA values (p=0.022, after multiple comparisons correction), but no significant differences in RD, MD, or AD measures. The study is the first to demonstrate microstructural changes in the SN of human subjects with chronic pesticide exposure. The changes detected by MRI may mark "one of the hits" leading to PD, and underlie the increased risk of PD in pesticide users found in epidemiological studies. Further human studies assisted by these imaging markers may be useful in understanding the etiology of PD.

Genetic analysis of the FBXO42 gene in Chinese Han patients with Parkinson's disease

Background

Parkinson’s disease (PD), the second most common neurodegenerative disease, is characterized by loss of dopaminergic neurons in the substantia nigra. The clinical manifestations of PD encompass a variety of motor and non-motor symptoms. Mutations in the F-box protein 7 gene (FBXO7) have been identified to cause Parkinsonian-pyramidal syndrome, an autosomal recessive form of Parkinsonism. The F-box protein 42 gene (FBXO42), a paralog of the FBXO7 gene, is involved in the ubiquitin-proteasome system that may play a role in the pathogenesis of PD.

Methods

To determine whether the FBXO42 gene is associated with PD, we performed a systematic genetic analysis of the FBXO42 gene in 316 PD patients and 295 gender-, age-, and ethnicity-matched normal controls.

Results

We identified a novel variant c.1407T>C (p.S469S) and three known single nucleotide variants, including rs2273311, rs12069239 and rs35196193 in the FBXO42 gene in PD patient group. None of the three known variants displayed statistically significant difference in either genotypic or allelic distributions between patient and control groups (all P > 0.05). Haplotype analysis showed that a common haplotype (G-C-G) for the three single nucleotide variants conferred a 1.69-fold increased risk for PD (P = 0.008 after Bonferroni correction, OR = 1.69, 95% CI = 1.06-2.71).

Conclusions

Our findings suggest that a haplotype of the FBXO42 gene might be associated with a higher susceptibility to PD.

The VPS35 gene and Parkinson's disease

Parkinson's disease (PD), the second most common age-related neurodegenerative disease, is characterized by loss of dopaminergic and nondopaminergic neurons, leading to a variety of motor and nonmotor symptoms. In addition to environmental factors, genetic predisposition and specific gene mutations have been shown to play an important role in the pathogenesis of this disorder. Recently, the identification of the vacuolar protein sorting 35 homolog gene (VPS35), linked to autosomal dominant late-onset PD, has provided new clues to the pathogenesis of PD. Here we discuss the VPS35 gene, its protein function, and various pathways involved in Wnt/β-catenin signaling and in the role of DMT1 mediating the uptake of iron and iron translocation from endosomes to the cytoplasm. Further understanding of these mechanisms will undoubtedly provide new insights into the pathogenic mechanisms of PD and may lead to prevention and better treatment of the disorder.

Cutting edge: IL-13Rα1 expression in dopaminergic neurons contributes to their oxidative stress-mediated loss following chronic peripheral treatment with lipopolysaccharide

Inflammation and its mediators, including cytokines and reactive oxygen species, are thought to contribute to neurodegeneration. In the mouse brain, we found that IL-13Rα1 was expressed in the dopaminergic (DA) neurons of the substantia nigra pars compacta, which are preferentially lost in human Parkinson's disease. Mice deficient for Il13ra1 exhibited resistance to loss of DA neurons in a model of chronic peripheral inflammation using bacterial LPS. IL-13, as well as IL-4, potentiated the cytotoxic effects of t-butyl hydroperoxide and hydrogen peroxide on mouse DA MN9D cells. Collectively, our data indicate that expression of IL-13Rα1 on DA neurons can increase their susceptibility to oxidative stress-mediated damage, thereby contributing to their preferential loss. In humans, Il13ra1 lies on the X chromosome within the PARK12 locus of susceptibility to Parkinson's disease, suggesting that IL-13Rα1 may have a role in the pathogenesis of this neurodegenerative disease.

Changes in clinical management and diagnosis following DaTscan SPECT imaging in patients with clinically uncertain parkinsonian syndromes: a 12-week follow-up study

BACKGROUND

An accurate diagnosis is important for timely and adequate treatment in patients with clinically uncertain parkinsonian syndrome (CUPS).

OBJECTIVE

The objective of this study was to assess safety and changes in clinical management, diagnosis and quality of life (QoL) at 4 and 12 weeks following DaTscan (ioflupane [(123)I] injection) imaging in patients with CUPS.

METHODS

This randomized, open-label, single-dose, multicenter trial was carried out in patients with CUPS who were randomized to either a DaTscan imaging group or to a control group without imaging. The main outcome measures were the proportions of patients with changes in clinical management and diagnosis from baseline through to 12 weeks after DaTscan. A total of 19 university hospital centers in Europe and the USA participated in the study. There were 267 patients enrolled and randomized (131 DaTscan, 136 control).

RESULTS

Significantly more DaTscan patients had changes in clinical management after 12 weeks (p = 0.004) compared to the control group, and significantly more DaTscan patients had changes in diagnosis at 4 weeks and at 12 weeks (both p < 0.001) compared to control patients. No significant difference in total score for QoL was observed between groups during the study duration. DaTscan was safe and well-tolerated. No deaths, serious adverse events (AEs) or withdrawals due to AEs occurred during the study. One patient had a headache following treatment with a suspected relationship to DaTscan.

CONCLUSION

DaTscan imaging significantly affected the clinical management and diagnosis of patients with CUPS. DaTscan is safe and well-tolerated and is a useful adjunct to differential diagnosis of CUPS.

Gender-related differences in the burden of non-motor symptoms in Parkinson's disease

Differences in the expression of non-motor symptoms (NMS) by Parkinson's disease (PD) patients may have important implications for their management and prognosis. Gender is a basic epidemiological variable that could influence such expression. The present study evaluated the prevalence and severity of NMS by gender in an international sample of 951 PD patients, 62.63% males, using the non-motor symptoms scale (NMSS). Assessments for motor impairment and complications, global severity, and health state were also applied. All disease stages were included. No significant gender differences were found for demographic and clinical characteristics. For the entire sample, the most prevalent symptoms were Nocturia (64.88%) and Fatigue (62.78%) and the most prevalent affected domains were Sleep/Fatigue (84.02%) and Miscellaneous (82.44%). Fatigue, feelings of nervousness, feelings of sadness, constipation, restless legs, and pain were more common and severe in women. On the contrary, daytime sleepiness, dribbling saliva, interest in sex, and problems having sex were more prevalent and severe in men. Regarding the NMSS domains, Mood/Apathy and Miscellaneous problems (pain, loss of taste or smell, weight change, and excessive sweating) were predominantly affected in women and Sexual dysfunction in men. No other significant differences by gender were observed. To conclude, in this study significant differences between men and women in prevalence and severity of fatigue, mood, sexual and digestive problems, pain, restless legs, and daytime sleepiness were found. Gender-related patterns of NMS involvement may be relevant for clinical trials in PD.

The Toll-like receptor-3 agonist polyinosinic:polycytidylic acid triggers nigrostriatal dopaminergic degeneration

In Parkinson's disease (PD), loss of striatal dopaminergic (DA) terminals and degeneration of DA neurons in the substantia nigra (SN) are associated with glial reactions. Such inflammatory processes are commonly considered an epiphenomenon of neuronal degeneration. However, there is increasing recognition of the role of neuroinflammation as an initiation factor of DA neuron degeneration. To investigate this issue, we established a new model of brain inflammation by injecting the Toll-like receptor 3 (TLR-3) agonist polyinosinic:polycytidylic acid [poly(I:C)] in the SN of adult rats. Poly(I:C) injection induced a sustained inflammatory reaction in the SN and in the dorsolateral striatum. Significant changes were detected in proteins relevant to synaptic transmission and axonal transport. In addition, cytoplasmic mislocalization of neuronal TAR DNA binding protein TDP-43 was observed. Poly(I:C) injection increased the susceptibility of midbrain DA neurons to a subsequent neurotoxic trigger (low-dose 6-hydroxydopamine). Systemic delivery of interleukin-1 receptor antagonist protected SN DA neurons exposed to combined poly(I:C) induced inflammatory and neurotoxic oxidative stress. These data indicate that viral-like neuroinflammation induces predegenerative changes in the DA system, which lowers the set point toward neuronal dysfunction and degeneration. New powerful neuroprotective therapies for PD might be considered by targeting critical inflammatory mechanisms, including cytokine-induced neurotoxicity.

Bone and mineral metabolism in older adults with Parkinson's disease

OBJECTIVES

Parkinson's disease (PD) and osteoporosis are two common chronic disabling conditions in older adults that adversely affect quality of life. The aim of the present work was to study the relationship between bone changes and PD.

METHODS

eighty-two patients with established PD aged 65 years or older and 68 age-, sex- and body mass index (BMI)-matched healthy control subjects were recruited. Exclusion criteria included other known causes of osteoporosis. Data including BMI, sunlight exposure, Hoehn and Yahr stage, disease duration and history of previous falls and/or fractures were collected. Bone mineral density was measured using dual energy x-ray absorptiometry. Sera were analysed for ionised calcium, vitamin D, bone alkaline phosphatase (BALP) and urinary N-terminal telopeptide of type I collagen (NTx). Physical and mental performance was also assessed.

RESULTS

the findings show that the bone mineral density (BMD) of all PD patients was significantly lower compared to controls. PD patients had significantly decreased vitamin D levels, significantly increased BALP and NTx levels, reduced physical and mental performance and more falls and/or fractures in comparison to healthy controls.

CONCLUSION

PD is associated with an increased incidence of osteoporosis, falls and fractures. PD is thus a risk factor for osteoporosis and appropriate therapeutic interventions should be initiated to slow or prevent disability.

Association between lifetime cigarette smoking and lewy body accumulation

Cigarette smoking has been associated repeatedly in observational studies with decreased risk of Parkinson's disease (PD), but its relationship to the risk of dementia or Alzheimer's disease (AD) is inconsistent. All of these studies have used clinical diagnoses of disease. We tested the hypothesis that lifetime cigarette use might be associated with reduced risk of neuropathologic changes of Lewy-related pathology (LRP) in multiple brain regions or with reduced risk of consensus neuropathologic changes of AD in a prospective community-based study of brain aging and dementia, the Adult Changes in Thought (ACT) study. We observed that heavy lifetime cigarette smoking (>50 pack years) was associated with significantly reduced relative risk (RR) for LRP, but not AD-type pathologic changes, after correcting for selection bias, and with significantly reduced frequency of LRP in the substantia nigra. These findings are the first of which we are aware to associate reduced LRP in human brain with any exposure, and substantiate observational studies that have associated cigarette smoking with reduced risk of PD. Although cigarette smoking is too toxic to suggest as a treatment, if confirmed, these findings may guide future therapeutic strategies that attempt to suppress LRP in human brain by other means.