Onset and progression factors in Parkinson's disease: A systematic review

Investigating Parkinson's disease risk across farming activities using data mining and large-scale administrative health data

The risk of Parkinson's disease (PD) associated with farming has received considerable attention, in particular for pesticide exposure. However, data on PD risk associated with specific farming activities is lacking. We aimed to explore whether specific farming activities exhibited a higher risk of PD than others among the entire French farm manager (FM) population. A secondary analysis of real-world administrative insurance claim data and electronic health/medical records (TRACTOR project) was conducted to estimate PD risk for 26 farming activities using data mining. PD cases were identified through chronic disease declarations and antiparkinsonian drug claims. There were 8845 PD cases among 1,088,561 FMs. The highest-risk group included FMs engaged in pig farming, cattle farming, truck farming, fruit arboriculture, and crop farming, with mean hazard ratios (HRs) ranging from 1.22 to 1.67. The lowest-risk group included all activities involving horses and small animals, as well as gardening, landscaping and reforestation companies (mean HRs: 0.48-0.81). Our findings represent a preliminary work that suggests the potential involvement of occupational risk factors related to farming in PD onset and development. Future research focusing on farmers engaged in high-risk farming activities will allow to uncover potential occupational factors by better characterizing the farming exposome, which could improve PD surveillance among farmers.

Associations of long-term exposure to low-level PM2.5 and brain disorders in 260,922 middle-aged and older adults

Long-term exposure to high-level ambient PM2.5 was associated with increased risks of brain disorders, while the associations remain uncertain when the exposure is lower than current air quality standards in numerous countries. This study aimed to assess the effects of PM2.5 exposure on the brain system in the population with annual mean concentrations ≤15 μg/m3. We analyzed data from 260,922 participants without preexisting brain diseases at baseline in the UK Biobank. The geographical distribution of PM2.5 in 2010 was estimated by a land use regression model and linked with individual residential address. We investigated associations of ambient PM2.5 with incident neurological (dementia, Parkinson's diseases [PD], epilepsy, and migraine) and psychiatric (major depressive disorder [MDD] and anxiety disorder) diseases through Cox proportional hazard models. We further estimated the links with brain imaging phenotypes by neuroimaging analysis. Results showed that in the population with PM2.5 concentrations ≤15 μg/m3, each interquartile range (IQR, 1.28 μg/m3) increment in PM2.5 was related to incidence risks of dementia, epilepsy, migraine, MDD, and anxiety disorder with hazard ratios of 1.08 (95% confidence interval [CI]: 1.03, 1.13), 1.12 (1.05, 1.20), 1.07 (1.00, 1.13), 1.06 (1.03, 1.09), and 1.05 (1.02, 1.08), respectively. We did not observe a significant association with PD. The association with dementia was stronger among the population with poor cardiovascular health (measured by Life's Essential 8) than the counterpart (P for interaction = 0.037). Likewise, per IQR increase was associated with specific brain imaging phenotypes, including volumes of total brain (β = -0.036; 95% CI: -0.050, -0.022), white matter (-0.030; -0.046, -0.014), grey matter (-0.030; -0.042, -0.017), respectively. The findings suggest long-term exposure to ambient PM2.5 at low-level still has an adverse impact on the neuro-psychiatric systems. The brain-relevant epidemiological assessment suggests that each country should update the standard for ambient PM2.5 following the World Health Organization Air Quality Guidelines 2021.

Advancements in Genetic and Biochemical Insights: Unraveling the Etiopathogenesis of Neurodegeneration in Parkinson's Disease

Parkinson's disease (PD) is the second most prevalent neurodegenerative movement disorder worldwide, which is primarily characterized by motor impairments. Even though multiple hypotheses have been proposed over the decades that explain the pathogenesis of PD, presently, there are no cures or promising preventive therapies for PD. This could be attributed to the intricate pathophysiology of PD and the poorly understood molecular mechanism. To address these challenges comprehensively, a thorough disease model is imperative for a nuanced understanding of PD's underlying pathogenic mechanisms. This review offers a detailed analysis of the current state of knowledge regarding the molecular mechanisms underlying the pathogenesis of PD, with a particular emphasis on the roles played by gene-based factors in the disease's development and progression. This study includes an extensive discussion of the proteins and mutations of primary genes that are linked to PD, including α-synuclein, GBA1, LRRK2, VPS35, PINK1, DJ-1, and Parkin. Further, this review explores plausible mechanisms for DAergic neural loss, non-motor and non-dopaminergic pathologies, and the risk factors associated with PD. The present study will encourage the related research fields to understand better and analyze the current status of the biochemical mechanisms of PD, which might contribute to the design and development of efficacious and safe treatment strategies for PD in future endeavors.

Association between socioeconomic status and Parkinson's disease: findings from a large incident case-control study

Introduction

The association between socioeconomic status (SES) and Parkinson's disease (PD) has been investigated in few studies. To our knowledge, SES measurement based on wealth index and perceived SES in PD patients has not been investigated in any study. Also, the simultaneous measurement of objective and perceived SES and their association with PD has not been conducted yet. This study aimed to determine the association between various SES indicators and PD.

Methods

This incident case-control study was conducted on 508 patients with PD and 1015 controls randomly selected from the general population in Iran in 2021-2022. A telephone interviewing method was used for data collection. The wealth index and educational level were used to measure objective SES. Perceived SES was also recorded. Multiple logistic regression was used to calculate the adjusted OR (AOR).

Results

A significant association based on the wealth index was found, where the intermediate category had lower odds of developing PD than the deprived category (AOR 0.75 (95% CI 0.58 to 0.99)). The odds of PD was significantly higher in the people with academic education compared with illiterate and primary-level education (AOR 2.17 (95% CI 1.58 to 2.99). Additionally, the odds of PD were significantly lower in the intermediate (AOR 0.26 (95% CI 0.13 to 0.52)) and affluent (AOR 0.21 (95% CI 0.11 to 0.40)), compared with the deprived categories based on perceived SES. Similar results were obtained in the analysis by sex.

Conclusion

This study demonstrated that lower wealth index, a lower perceived SES and academic education are associated with increased the odds of PD.

Environmental and genetic risk factors for Parkinson’s disease

Aim. To analyze risk factors in the group of patients with Parkinson’s disease (PD) and compare them with the literature data.

Materials and methods. The study included 439 patients with PD and 354 controls, comparable by gender and age. For each individual, a registration card was filled in containing demographic, epidemiological, clinical, and neuropsychological data. The severity of the disease was studied according to the MDS-UPDRS scale; the stage of PD was determined according to the Hoehn and Yahr scale. Cognitive functions were assessed by the MoCA test and MMSE. The length of the (CAG)n repeat region in the HTT gene was determined using fragment analysis on the ABI 3730 DNA analyzer. The obtained results were analyzed using GeneMapper Software v4.1 (Applied Biosystems, USA).

Results. When comparing patients with PD and the control group, the odds ratio (OR) for PD in individuals with traumatic brain injury was 3.13 (95% confidence interval (CI): 2,27–4.34; p = 4.94 × 10–13), which showed the significance of this risk factor for PD. Consumption of coffee in the anamnesis distinguished the group of PD patients from the control group (OR = 0.41 (95% CI: 0.30–0.56); p < 0.0001), confirming its neuroprotective effect. Analysis of the variability in the length of the (CAG)n repeat regions in the HTT gene showed that patients whose genotype contained an allele with 17 repeats in combination with any allele other than an allele containing 18 repeats had a protective effect (OR = 0.50 (95% CI: 0.27–0.92); p = 0.025). All genotypes containing an allele with 18 repeats were predisposed to PD (OR = 2.57 (95% CI: 1.66–4.28); p = 0.007). The predisposing effect of the allele to PD, unrelated to the expansion of CAG repeats in the HTT gene, was revealed for the first time.

Conclusion. Traumatic brain injury and the allele with 18 CAG repeats in the HTT gene are risk factors for PD. Coffee consumption can be attributed to protective factors in relation to PD.

Molecular and Cellular Interactions in Pathogenesis of Sporadic Parkinson Disease

An increasing number of the population all around the world suffer from age-associated neurodegenerative diseases including Parkinson’s disease (PD). This disorder presents different signs of genetic, epigenetic and environmental origin, and molecular, cellular and intracellular dysfunction. At the molecular level, α-synuclein (αSyn) was identified as the principal molecule constituting the Lewy bodies (LB). The gut microbiota participates in the pathogenesis of PD and may contribute to the loss of dopaminergic neurons through mitochondrial dysfunction. The most important pathogenetic link is an imbalance of Ca²⁺ ions, which is associated with redox imbalance in the cells and increased generation of reactive oxygen species (ROS). In this review, genetic, epigenetic and environmental factors that cause these disorders and their cause-and-effect relationships are considered. As a constituent of environmental factors, the example of organophosphates (OPs) is also reviewed. The role of endothelial damage in the pathogenesis of PD is discussed, and a ‘triple hit hypothesis’ is proposed as a modification of Braak’s dual hit one. In the absence of effective therapies for neurodegenerative diseases, more and more evidence is emerging about the positive impact of nutritional structure and healthy lifestyle on the state of blood vessels and the risk of developing these diseases.

Mitochondria-lysosome crosstalk in GBA1-associated Parkinson's disease

Organelle crosstalk is significant in regulating their respective functions and subsequent cell fate. Mitochondria and lysosomes are amongst the essential organelles in maintaining cellular homeostasis. Mitochondria-lysosome connections, which may develop dynamically in the human neurons, have been identified as sites of bidirectional communication. Aberrancies are often associated with neurodegenerative disorders like Parkinson's disease (PD), suggesting the physical and functional link between these two organelles. PD is often linked with genetic mutations of several mutations discovered in the familial forms of the disease; some are considered risk factors. Many of these genes are either associated with mitochondrial function or belong to endo-lysosomal pathways. The recent investigations have indicated that neurons with mutant glucosylceramidase beta (GBA1) exhibit extended mitochondria-lysosome connections in individuals with PD. This may be due to impaired control of the untethering protein, which aids in the hydrolysis of Rab7 GTP required for contact untethering. A GCase modulator may be used to augment the reduced GBA1 lysosomal enzyme activity in the neurons of PD patients. This review focuses on how GBA1 mutation in PD is interlinked with mitochondria-lysosome (ML) crosstalk, exploring the pathways governing these interactions and mechanistically comprehending the mitochondrial and lysosomal miscommunication in the pathophysiology of PD. This review is based on the limited literature available on the topic and hence may be subject to bias in its views. Our estimates may be conservative and limited due to the lack of studies under the said discipline due to its inherent complex nature. The current association of GBA1 to PD pathogenesis is based on the limited scope of study and further research is necessary to explore the risk factors further and identify the relationship with more detail.

Risk Factors of Parkinson’s Disease: A Case-Control Study in Moroccan Patients

Background: Parkinson’s disease (PD) remains a significant health concern in Morocco. Multivariate analysis was not used in any study to evaluate the role of various factors that contributed to the onset of the disease. Objectives: This study investigates the role of family, environmental, and professional factors in PD development. Methods: The present study is an age-matched case-control study with risk estimation based on odds ratios (OR) with a 95% confidence interval (CI). In total, 180 cases were matched with 360 controls. Results: The average age of participants was 68.3 ± 11.2 years. Adjusted logistic regression analysis showed that the family history of PD (ORa = 7.19, CI 95% 3.41 - 15.13), male sex (ORa = 1.92, CI 95% 1.16 - 3.16), spring water consumption (ORa = 3.31, CI 95% 2.05 - 5.34), drug use (ORa = 2.12, CI 95% 1.33 - 3.38), a history of head injury (ORa = 3.38, CI 95% 1.16 - 9.83) and non - consumption of coffee (ORa = 3.04, CI 95% 1.56 - 5.90) were significantly associated with the onset of the disease. In a univariate analysis, well water consumption was observed as a significant risk factor but could not be shown to be significant in a multivariate analysis. Previous work on a farm (ORa = 0.30, CI 95% 0.16 - 0.54) and history of general anesthesia (ORa = 0.47, CI 95% 0.27 - 0.83) were inversely associated with PD risk. No statistical significance was observed in the data on occupational exposure and disease risk, although there was a 30% decrease in risk for the service occupations (ORa = 0.05, CI 95% 0.01 - 0.18). Conclusions: As a result, further research is needed to determine additional risk factors.

Genomic instability evaluation by BMCyt and telomere length in Brazilian family farmers exposed to pesticides

Brazil is one of the largest consumers of pesticides in the world. This high consumption has resulted in higher potential health risk to agricultural farm workers due to occupational exposure. Hence, the aim of this study is to evaluate genomic instability, using Buccal Micronucleus Cytome (BMCyt) and telomere length (TL) measurement as biomarkers of occupational exposure to pesticides in rural workers living in the State of São Paulo, Brazil. Genomic instability was evaluated in 81 pesticide-exposed farm workers (69 males and 12 females) with a mean age of 49.16 ± 10.06 years and a mean time job of 30.00 ± 14.00 years,81 non-exposed individuals (62 males and 15 females) with a mean age of 47.87 ± 10.66 years. BMCyt results showed significantly higher levels of cell damage (micronuclei and binucleated cells) and cell death (karyorrhectic and condensed chromatin cells) in subjects exposed to pesticide when compared to those non-exposed (p < 0.05). Although our results did not show significant differences in TL among exposed and non-exposed groups, effects in TL due to pesticide exposure was found in a multivariable linear regression model when we stratified the groups by age (≤ 49 years and ≥ 50 years old; β = 11.21, p = 0.006). In addition, TL reduction on was identified in relation to an increase in cigarette pack consumption (β = -0.633, p = 0.045). Furthermore, exposure to specific pesticides presented different effects in TL. Cypermethrin exposure resulted in a reduction in TL (β = -18.039, p = 0.018), while abamectin exposure led to an increase in TL (β = 23.990, p = 0.007). Thus, our findings substantiate genomic instability due to pesticides exposure.

A feasibility pilot study of the effects of neurostimulation on swallowing function in Parkinson’s Disease

Introduction

Dysphagia often occurs during Parkinson’s disease (PD) and can have severe consequences. Recently, neuromodulatory techniques have been used to treat neurogenic dysphagia. Here we aimed to compare the neurophysiological and swallowing effects of three different types of neurostimulation, 5 Hertz (Hz) repetitive transcranial magnetic stimulation (rTMS), 1 Hz rTMS and pharyngeal electrical stimulation (PES) in patients with PD.

Method

12 PD patients with dysphagia were randomised to receive either 5 Hz rTMS, 1 Hz rTMS, or PES. In a cross-over design, patients were assigned to one intervention and received both real and sham stimulation. Patients received a baseline videofluoroscopic (VFS) assessment of their swallowing, enabling penetration aspiration scores (PAS) to be calculated for: thin fluids, paste, solids and cup drinking. Swallowing timing measurements were also performed on thin fluid swallows only. They then had baseline recordings of motor evoked potentials (MEPs) from both pharyngeal and (as a control) abductor pollicis brevis (APB) cortical areas using single-pulse TMS. Subsequently, the intervention was administered and post interventional TMS recordings were taken at 0 and 30 minutes followed by a repeat VFS within 60 minutes of intervention.

Results

All interventions were well tolerated. Due to lower than expected recruitment, statistical analysis of the data was not undertaken. However, with respect to PAS swallowing timings and MEP amplitudes, there was small but visible difference in the outcomes between active and sham.

Conclusion

PES, 5 Hz rTMS and 1 Hz rTMS are tolerable interventions in PD related dysphagia. Due to small patient numbers no definitive conclusions could be drawn from the data with respect to individual interventions improving swallowing function and comparative effectiveness between interventions. Larger future studies are needed to further explore the efficacy of these neuromodulatory treatments in Parkinson’s Disease associated dysphagia.

Coffee, smoking and aspirin are associated with age at onset in idiopathic Parkinson's disease

Parkinson’s disease (PD) is a progressive neurodegenerative disorder. Genetic modifiers, environmental factors and gene–environment interactions have been found to modify PD risk and disease progression. The objective of this study was to evaluate the association of smoking, caffeine and anti-inflammatory drugs with age at onset (AAO) in a large PD cohort. A total of 35,963 American patients with idiopathic PD (iPD) from the Fox Insight Study responded to health and lifestyle questionnaires. We compared the median AAO between different groups using the non-parametric Mann–Whitney U test. Non-parametric Spearman’s correlation was used for correlation assessments and regression analysis was used to assess interaction between variables. We found that smoking (p < 0.0001), coffee drinking (p < 0.0001) and aspirin intake (p < 0.0001) show an exploratory association with AAO in PD, that was further supported by multivariate regression models. The association of aspirin with PD AAO was replicated in another cohort (EPIPARK) (n = 237 patients with PD).

Analysis of serum levels of organochlorine pesticides and related factors in Parkinson's disease

BACKGROUND

There is evidence that environmental factors contribute to the onset and progression of Parkinson's disease (PD). Pesticides are a class of environmental toxins that are linked to increased risk of developing PD. However, few studies have investigated the association between specific pesticides and PD, especially in China, which was one of the first countries to adopt the use of pesticides.

METHODS

In this study, serum levels of 19 pesticides were measured in 90 patients with PD and 90 healthy spouse controls. We also analyzed the interaction between specific pesticides and PD. In addition, the association between pesticides and clinical features of PD was also investigated. Finally, we investigated the underlying mechanism of the association between pesticides and PD.

RESULTS

Serum levels of organochlorine pesticides, which included α-hexachlorocyclohexane (HCH), β-HCH, γ-HCH, δ-HCH, propanil, heptachlor, dieldrin, hexachlorobenzene, p,p'-dichlorodiphenyltrichloroethane and o,p'-dichloro-diphenyl-trichloroethane were higher in PD patients than controls. Moreover, α-HCH and propanil levels were associated with PD. Serum levels of dieldrin were associated with Hamilton Depression Scale and Montreal Cognitive Assessment scores in PD patients. In SH-SY5Y cells, α-HCH and propanil increased level of reactive oxygen species and decreased mitochondrial membrane potential. Furthermore, propanil, but not α-HCH, induced the aggregation of α-synuclein.

CONCLUSIONS

This study revealed that elevated serum levels of α-HCH and propanil were associated with PD. Serum levels of dieldrin were associated with depression and cognitive function in PD patients. Moreover, propanil, but not α-HCH, induced the aggregation of α-synuclein. Further research is needed to fully elucidate the effects of pesticides on PD.

Potential Effects of Leukotriene Receptor Antagonist Montelukast in Treatment of Neuroinflammation in Parkinson's Disease

Parkinson’s disease (PD) is a neurodegenerative disorder where misfolded alpha-synuclein-enriched aggregates called Lewy bodies are central in pathogenesis. No neuroprotective or disease-modifying treatments are currently available. Parkinson’s disease is considered a multifactorial disease and evidence from multiple patient studies and animal models has shown a significant immune component during the course of the disease, highlighting immunomodulation as a potential treatment strategy. The immune changes occur centrally, involving microglia and astrocytes but also peripherally with changes to the innate and adaptive immune system. Here, we review current understanding of different components of the PD immune response with a particular emphasis on the leukotriene pathway. We will also describe evidence of montelukast, a leukotriene receptor antagonist, as a possible anti-inflammatory treatment for PD.

Effects of music-based movement therapy on motor function, balance, gait, mental health, and quality of life for patients with Parkinson's disease: A systematic review and meta-analysis

OBJECTIVE

To conduct a systematic review evaluating the effects of music-based movement therapy on motor function, balance, gait, mental health, and quality of life among individuals with Parkinson's disease.

DATA SOURCES

A systematic search of PubMed, Embase, Cochrane Library, Web of Science, PsycINFO, CINAHL, and Physiotherapy Evidence Database was carried out to identify eligible papers published up to December 10, 2020.

REVIEW METHODS

Literature selection, data extraction, and methodological quality assessment were independently performed by two investigators. Publication bias was determined by funnel plot and Egger's regression test. "Trim and fill" analysis was performed to adjust any potential publication bias.

RESULTS

Seventeen studies involving 598 participants were included in this meta-analysis. Music-based movement therapy significantly improved motor function (Unified Parkinson's Disease Rating Scale motor subscale, MD = -5.44, P = 0.002; Timed Up and Go Test, MD = -1.02, P = 0.001), balance (Berg Balance Scale, MD = 2.02, P < 0.001; Mini-Balance Evaluation Systems Test, MD = 2.95, P = 0.001), freezing of gait (MD = -2.35, P = 0.039), walking velocity (MD = 0.18, P < 0.001), and mental health (SMD = -0.38, P = 0.003). However, no significant effects were observed on gait cadence, stride length, and quality of life.

CONCLUSION

The findings of this study show that music-based movement therapy is an effective treatment approach for improving motor function, balance, freezing of gait, walking velocity, and mental health for patients with Parkinson's disease.

Clinical and Epidemiological Aspects of Parkinson's Disease in the South of Western Siberia

Background: The article is devoted to one of the most common neurodegenerative diseases in the world-Parkinson's disease (PD), the prevalence of which in Russia reaches 140-150 people per 100,000 people. The clinical and anamnestic profile of a patient with PD is presented, the prevalence of motor and non-motor symptoms is reflected, and a comparative characteristic of the neurological deficit in the Siberian population of patients with other cohorts of patients with Parkinson's disease in different countries and ethnic groups is presented. Methods: We studied 140 patients with Parkinson's disease. A comprehensive assessment of neurological status was performed using the "Unified Parkinson's Disease Rating Scale (UPDRS)." In addition, we used the Beck Depression and MoCA scale test. Assessment of the presence and severity of olfactory dysfunction was performed using the Sniffin Stick odor identification test. The stage of PD was evaluated according to the classification of M. M. Hoehn and M. D. Yahr. Results: The cohort of the study was dominated by overweight patients with a higher level of education, with concomitant arterial hypertension, coronary heart disease, and dyslipidemia. The severity of motor and most non-motor symptoms directly correlates with the duration of PD and the stage of the disease. The predominant form of the disease was a mixed form, which was also noted in research cohorts in Canada and the UK. The Siberian cohort tends to be more prevalent in hyposmia, daytime sleepiness, orthostatic hypotension, and depressive and REM disorders. Conclusion: Our data show the importance of a comprehensive assessment of both motor and non-motor neurological deficits as well as the analysis of comorbid disorders and risk factors for the occurrence and progression of Parkinson's disease. They also show the prevalence of certain motor and non-motor symptoms in the Siberian cohort of patients with Parkinson's disease.

The Effect of Caffeine on the Risk and Progression of Parkinson's Disease: A Meta-Analysis

Coffee and caffeine are speculated to be associated with the reduced risk of Parkinson's disease (PD). The present study aimed to investigate the disease-modifying potential of caffeine on PD, either for healthy people or patients, through a meta-analysis. The electronic databases were searched using terms related to PD and coffee and caffeinated food products. Articles were included only upon fulfillment of clear diagnostic criteria for PD and details regarding their caffeine content. Reference lists of relevant articles were reviewed to identify eligible studies not shortlisted using these terms. In total, the present study enrolled 13 studies, nine were categorized into a healthy cohort and the rest into a PD cohort. The individuals in the healthy cohort with regular caffeine consumption had a significantly lower risk of PD during follow-up evaluation (hazard ratio (HR) = 0.797, 95% CI = 0.748-0.849, p < 0.001). The outcomes of disease progression in PD cohorts included dyskinesia, motor fluctuation, symptom onset, and levodopa initiation. Individuals consuming caffeine presented a significantly lower rate of PD progression (HR = 0.834, 95% CI = 0.707-0.984, p = 0.03). In conclusion, caffeine modified disease risk and progression in PD, among both healthy individuals or those with PD. Potential biological benefits, such as those obtained from adenosine 2A receptor antagonism, may require further investigation for designing new drugs.

A Scientometric Analysis and Visualization of Research on Parkinson's Disease Associated With Pesticide Exposure

The etiology and pathogenesis of Parkinson's disease (PD) have not yet been clearly described. Both genetic and environmental factors contribute to the onset and progression of PD. Some pesticides have been demonstrated to be associated with PD by many previous studies and experiments, and an increasing number of researchers have paid attention to this area in recent years. This paper aims to explore the knowledge structure, analyze the current research hot spots, and discuss the research trend through screening and summarizing the present literature. Based on 1767 articles from the Web of Science Core Collection and PubMed database, this study carried out the analysis from the keywords, cited references, countries, authors, and some other aspects by using Citespace. The hot topics, valuable articles, and productive authors in this research field could be found after that. To the best of our knowledge, this is the first study to specifically visualize the relationship between pesticide exposure and PD, and forecast research tendency in the future.

Prognostic factors of Rapid symptoms progression in patients with newly diagnosed parkinson's disease

Tracking symptoms progression in the early stages of Parkinson's disease (PD) is a laborious endeavor as the disease can be expressed with vastly different phenotypes, forcing clinicians to follow a multi-parametric approach in patient evaluation, looking for not only motor symptomatology but also non-motor complications, including cognitive decline, sleep problems and mood disturbances. Being neurodegenerative in nature, PD is expected to inflict a continuous degradation in patients' condition over time. The rate of symptoms progression, however, is found to be even more chaotic than the vastly different phenotypes that can be expressed in the initial stages of PD. In this work, an analysis of baseline PD characteristics is performed using machine learning techniques, to identify prognostic factors for early rapid progression of PD symptoms. Using open data from the Parkinson's Progression Markers Initiative (PPMI) study, an extensive set of baseline patient evaluation outcomes is examined to isolate determinants of rapid progression within the first two and four years of PD. The rate of symptoms progression is estimated by tracking the change of the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) total score over the corresponding follow-up period. Patients are ranked according to their progression rates and those who expressed the highest rates of MDS-UPDRS total score increase per year of follow-up period are assigned into the rapid progression class, using 5- and 10-quantiles partition. Classification performance against the rapid progression class was evaluated in a per quantile partition analysis scheme and in quantile-independent approach, respectively. The results shown a more accurate patient discrimination with quantile partitioning, however, a much more compact subset of baseline factors is extracted in the latter, making a more suitable for actual interventions in practice. Classification accuracy improved in all cases when using the longer 4-year follow-up period to estimate PD progression, suggesting that a prolonged patient evaluation can provide better outcomes in identifying rapid progression phenotype. Non-motor symptoms are found to be the main determinants of rapid symptoms progression in both follow-up periods, with autonomic dysfunction, mood impairment, anxiety, REM sleep behavior disorders, cognitive decline and memory impairment being alarming signs at baseline evaluation, along with rigidity symptoms, certain laboratory blood test results and genetic mutations.

Genetic and Environmental Factors Contributing to Parkinson's Disease: A Case-Control Study in the Cypriot Population

Introduction: Parkinson's disease (PD) is a neurodegenerative disorder affecting a substantial proportion of the elderly Cypriot population. The objective of this study was to evaluate PD risk variants that have been identified previously in Genome Wide Association Studies (GWAS) and to find environmental factors that are predictors for PD onset in the Cypriot population.

Methods: A case-control study was conducted with a total of 235 PD patients and 464 healthy controls of Greek-Cypriot ethnicity. Demographic and lifestyle characteristics, exposure to PD risk factors and clinical data were collected. Moreover, 13 previously GWAS-identified PD risk variants were genotyped. Univariate and multivariate regression analyses examined the association between a number of environmental and genetic factors and PD.

Results: Multivariable regression analysis revealed that exposure to both pesticides and other toxic substances (P = 0.03), severe head injury accompanied with fainting (P = 0.001), nuts consumption (P = 0.004), red meat consumption (P = 0.02), and soft drinks consumption (P = 0.008) were increasing the risk for PD, whereas cumulative smoking (P = 0.02), and fish consumption (P = 0.02) were decreasing the risk for PD. Five out of the 13 tested SNPs (rs12185268, rs6599389, rs356220, rs13312, and rs17649553) were confirmed to be nominally significantly associated (P < 0.05) with PD risk in the Cypriot population.

Conclusions: Collectively, this case-control study has shed some light on the nature of PD epidemiology in Cyprus, by demonstrating a number of genetic and environmental determinants of PD in the Cypriot population.

Occupation and Parkinson disease in the Women's Health Initiative Observational Study

INTRODUCTION

There is a lack of consistent study findings on associations between workplace exposures and the risk of Parkinson disease (PD) and a paucity of such data on women. We assessed PD risk among occupational groups to derive insights about potential occupation-specific exposures in a large cohort of women.

METHODS

The Women's Health Initiative Observational Study (WHI-OS) is a prospective cohort that enrolled 91 627 postmenopausal women, 50 to 79 years of age, from 01 October 1993 through 31 December 1998, at 40 clinical centers across the United States, with average follow-up interval of 11 years. These women reported up to three paid jobs, held the longest since age 18; these jobs were coded and duration of employment calculated. We defined a case by self-report of doctor-diagnosed PD (at baseline or follow-up), death attributed to PD, or taking medication consistent with PD.

RESULTS

Among 2590 PD cases, we found evidence of excess risk among "counselors, social workers, and other community and social service specialists," and there was a suggestion of increased in risk among postsecondary teachers, and "building and grounds cleaning and maintenance" workers. There was also evidence of a deficit in risk among women who worked in sales. Results according to ever-employed and job duration were similar, except for evidence of excess risk among "health technologists and technicians" with more than 20 years of employment. Longer duration of life on a farm was associated with higher risk.

CONCLUSION

Our findings paint a largely reassuring picture of occupational risks for PD among US women.

Neurotoxicity of polychlorinated biphenyls and related organohalogens

Halogenated organic compounds are pervasive in natural and built environments. Despite restrictions on the production of many of these compounds in most parts of the world through the Stockholm Convention on Persistent Organic Pollutants (POPs), many "legacy" compounds, including polychlorinated biphenyls (PCBs), are routinely detected in human tissues where they continue to pose significant health risks to highly exposed and susceptible populations. A major concern is developmental neurotoxicity, although impacts on neurodegenerative outcomes have also been noted. Here, we review human studies of prenatal and adult exposures to PCBs and describe the state of knowledge regarding outcomes across domains related to cognition (e.g., IQ, language, memory, learning), attention, behavioral regulation and executive function, and social behavior, including traits related to attention-deficit hyperactivity disorder (ADHD) and autism spectrum disorders (ASD). We also review current understanding of molecular mechanisms underpinning these associations, with a focus on dopaminergic neurotransmission, thyroid hormone disruption, calcium dyshomeostasis, and oxidative stress. Finally, we briefly consider contemporary sources of organohalogens that may pose human health risks via mechanisms of neurotoxicity common to those ascribed to PCBs.

Time Trends of the Incidence, Prevalence, and Mortality of Parkinsonism

Objectives:We assessed trends in the incidence, prevalence, and post-diagnosis mortality of parkinsonism in Ontario, Canada over 18 years. We also explored the influence of a range of risk factors for brain health on the trend of incident parkinsonism.Methods:We established an open cohort by linking population-based health administrative databases from 1996 to 2014 in Ontario. The study population comprised residents aged 20–100 years with an incident diagnosis of parkinsonism ascertained using a validated algorithm. We calculated age- and sex-standardized incidence, prevalence, and mortality of parkinsonism, stratified by young onset (20–39 years) and mid/late onset (≥40 years). We assessed trends in incidence using Poisson regression, mortality using negative binomial regression, and prevalence of parkinsonism and pre-existing conditions (e.g., head injury) using the Cochran–Armitage trend test. To better understand trends in the incidence of mid/late-onset parkinsonism, we adjusted for various pre-existing conditions in the Poisson regression model.Results:From 1996 to 2014, we identified 73,129 incident cases of parkinsonism (source population of ∼10.5 million), of whom 56% were male, mean age at diagnosis was 72.6 years, and 99% had mid/late-onset parkinsonism. Over 18 years, the age- and sex-standardized incidence decreased by 13.0% for mid/late-onset parkinsonism but remained unchanged for young-onset parkinsonism. The age- and sex-standardized prevalence increased by 22.8%, while post-diagnosis mortality decreased by 5.5%. Adjustment for pre-existing conditions did not appreciably explain the declining incidence of mid/late-onset parkinsonism.Conclusion:Young-onset and mid/late-onset parkinsonism exhibited differing trends in incidence over 18 years in Ontario. Further research to identify other factors that may appreciably explain trends in incident parkinsonism is warranted.

Determinants of neurological disease: Synthesis of systematic reviews

Systematic reviews were conducted to identify risk factors associated with the onset and progression of 14 neurological conditions, prioritized as a component of the National Population Health Study of Neurological Conditions. These systematic reviews provided a basis for evaluating the weight of evidence of evidence for risk factors for the onset and progression of the 14 individual neurological conditions considered. A number of risk factors associated with an increased risk of onset for more than one condition, including exposure to pesticides (associated with an increased risk of AD, amyotrophic lateral sclerosis, brain tumours, and PD; smoking (AD, MS); and infection (MS, Tourette syndrome). Coffee and tea intake was associated with a decreased risk of onset of both dystonia and PD. Further understanding of the etiology of priority neurological conditions will be helpful in focusing future research initiatives and in the development of interventions to reduce the burden associated with neurological conditions in Canada and internationally.