Parkinson's disease and occupation: differences in associations by case identification method suggest referral bias

Impact of genetic predisposition to late-onset neurodegenerative diseases on early life outcomes and brain structure

Most patients with late-onset neurodegenerative diseases such as Alzheimer's and Parkinson's have a complex aetiology resulting from numerous genetic risk variants of small effects located across the genome, environmental factors, and the interaction between genes and environment. Over the last decade, genome-wide association studies (GWAS) and post-GWAS analyses have shed light on the polygenic architecture of these diseases, enabling polygenic risk scores (PRS) to estimate an individual's relative genetic liability for presenting with the disease. PRS can screen and stratify individuals based on their genetic risk, potentially years or even decades before the onset of clinical symptoms. An emerging body of evidence from various research studies suggests that genetic susceptibility to late-onset neurodegenerative diseases might impact early life outcomes, including cognitive function, brain structure and function, and behaviour. This article summarises recent findings exploring the potential impact of genetic susceptibility to neurodegenerative diseases on early life outcomes. A better understanding of the impact of genetic susceptibility to neurodegenerative diseases early in life could be valuable in disease screening, detection, and prevention and in informing treatment strategies before significant neural damage has occurred. However, ongoing studies have limitations. Overall, our review found several studies focused on APOE haplotypes and Alzheimer's risk, but a limited number of studies leveraging polygenic risk scores or focused on genetic susceptibility to other late-onset conditions.

Neurotoxicity of Titanium Dioxide Nanoparticles: A Comprehensive Review

The increasing use of titanium dioxide nanoparticles (TiO2 NPs) across various fields has led to a growing concern regarding their environmental contamination and inevitable human exposure. Consequently, significant research efforts have been directed toward understanding the effects of TiO2 NPs on both humans and the environment. Notably, TiO2 NPs exposure has been associated with multiple impairments of the nervous system. This review aims to provide an overview of the documented neurotoxic effects of TiO2 NPs in different species and in vitro models. Following exposure, TiO2 NPs can reach the brain, although the specific mechanism and quantity of particles that cross the blood-brain barrier (BBB) remain unclear. Exposure to TiO2 NPs has been shown to induce oxidative stress, promote neuroinflammation, disrupt brain biochemistry, and ultimately impair neuronal function and structure. Subsequent neuronal damage may contribute to various behavioral disorders and play a significant role in the onset and progression of neurodevelopmental or neurodegenerative diseases. Moreover, the neurotoxic potential of TiO2 NPs can be influenced by various factors, including exposure characteristics and the physicochemical properties of the TiO2 NPs. However, a systematic comparison of the neurotoxic effects of TiO2 NPs with different characteristics under various exposure conditions is still lacking. Additionally, our understanding of the underlying neurotoxic mechanisms exerted by TiO2 NPs remains incomplete and fragmented. Given these knowledge gaps, it is imperative to further investigate the neurotoxic hazards and risks associated with exposure to TiO2 NPs.

Sex and gender differences in Alzheimer's disease, Parkinson's disease, and Amyotrophic Lateral Sclerosis: a narrative review

Neurodegenerative diseases (NDs), including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS), exhibit high phenotypic variability and they are very common in the general population. These diseases are associated with poor prognosis and a significant burden on patients and their caregivers. Although increasing evidence suggests that biological sex is an important factor for the development and phenotypical expression of some NDs, the role of sex and gender in the diagnosis and prognosis of NDs has been poorly explored. Current knowledge relating to sex- and gender-related differences in the epidemiology, clinical features, biomarkers, and treatment of AD, PD, and ALS will be summarized in this narrative review. The cumulative evidence hitherto collected suggests that sex and gender are factors to be considered in explaining the heterogeneity of these NDs. Clarifying the role of sex and gender in AD, PD, and ALS is a key topic in precision medicine, which will facilitate sex-specific prevention and treatment strategies to be implemented in the near future.

High IQ in Early Adulthood Is Associated with Parkinson's Disease

Background:

High education level and high occupational complexity have been implicated as risk factors for Parkinson’s disease (PD).

Objective:

The objective was to determine whether cognitive capacity, measured as IQ, in early adulthood is associated with the subsequent development of PD.

Method:

Data on IQ were retrieved from the Swedish Military Service Conscription Registry, comprising Swedish males who enlisted for military service in the period 1968–1993 (N = 1,319,235). After exclusion, 1,189,134 subjects in total were included in the present study. Individuals who later developed PD (N = 1,724) were identified using the Swedish National Patient Register and the Swedish Cause of Death Register.

Results:

High education level was associated with PD. High IQ was associated with PD (p < 0.0001), both when analyzed as a continuous variable and when divided into three categories. The hazard ratio for the high IQ category compared to the low IQ category was 1.35 (95% confidence interval 1.17–1.55). Strong test results on the subtests, measuring verbal, logic, visuospatial and technical abilities, were also associated with PD. In a subgroup, smoking was inversely associated with PD, as well as with IQ.

Conclusions:

This study identifies high IQ to be a risk factor for PD.

PKC Delta Activation Promotes Endoplasmic Reticulum Stress (ERS) and NLR Family Pyrin Domain-Containing 3 (NLRP3) Inflammasome Activation Subsequent to Asynuclein-Induced Microglial Activation: Involvement of Thioredoxin-Interacting Protein (TXNIP)/Thioredoxin (Trx) Redoxisome Pathway

A classical hallmark of Parkinson's disease (PD) pathogenesis is the accumulation of misfolded alpha-synuclein (αSyn) within Lewy bodies and Lewy neurites, although its role in microglial dysfunction and resultant dopaminergic (DAergic) neurotoxicity is still elusive. Previously, we identified that protein kinase C delta (PKCδ) is activated in post mortem PD brains and experimental Parkinsonism and that it participates in reactive microgliosis; however, the relationship between PKCδ activation, endoplasmic reticulum stress (ERS) and the reactive microglial activation state in the context of α-synucleinopathy is largely unknown. Herein, we show that oxidative stress, mitochondrial dysfunction, NLR family pyrin domain containing 3 (NLRP3) inflammasome activation, and PKCδ activation increased concomitantly with ERS markers, including the activating transcription factor 4 (ATF-4), serine/threonine-protein kinase/endoribonuclease inositol-requiring enzyme 1α (p-IRE1α), p-eukaryotic initiation factor 2 (eIF2α) as well as increased generation of neurotoxic cytokines, including IL-1β in aggregated αSyn_agg-stimulated primary microglia. Importantly, in mouse primary microglia-treated with αSyn_agg we observed increased expression of Thioredoxin-interacting protein (TXNIP), an endogenous inhibitor of the thioredoxin (Trx) pathway, a major antioxidant protein system. Additionally, αSyn_agg promoted interaction between NLRP3 and TXNIP in these cells. In vitro knockdown of PKCδ using siRNA reduced ERS and led to reduced expression of TXNIP and the NLRP3 activation response in αSyn_agg-stimulated mouse microglial cells (MMCs). Additionally, attenuation of mitochondrial reactive oxygen species (mitoROS) via mito-apocynin and amelioration of ERS via the eIF2α inhibitor salubrinal (SAL) reduced the induction of the ERS/TXNIP/NLRP3 signaling axis, suggesting that mitochondrial dysfunction and ERS may act in concert to promote the αSyn_agg-induced microglial activation response. Likewise, knockdown of TXNIP by siRNA attenuated the αSyn_agg-induced NLRP3 inflammasome activation response. Finally, unilateral injection of αSyn preformed fibrils (αSyn_PFF) into the striatum of wild-type mice induced a significant increase in the expression of nigral p-PKCδ, ERS markers, and upregulation of the TXNIP/NLRP3 inflammasome signaling axis prior to delayed loss of TH⁺ neurons. Together, our results suggest that inhibition of ERS and its downstream signaling mediators TXNIP and NLRP3 might represent novel therapeutic avenues for ameliorating microglia-mediated neuroinflammation in PD and other synucleinopathies.

Design and Preliminary Performance Assessment of a Wearable Tremor Suppression Glove

OBJECTIVE

Approximately 25% of individualsliving with parkinsonian tremor do not respond to traditional treatments. Wearable tremor suppression devices (WTSD) provide an alternative approach, however, tremor in the fingers has not been given as much attention as tremor in the elbow and the wrist. Therefore, the objective of this study is to design a wearable tremor suppression glove that can suppress tremor simultaneously, but independently, in multiple hand joints without restricting the user's voluntary motion.

METHODS

A WTSD was designed for managing tremor in the index finger metacarpophalangeal (MCP) joint, thumb MCP joint, and the wrist. The prototype was tested and assessed on a participant living with parkinsonian tremor.

RESULTS

The experimental evaluation showed an overall suppression of 73.1%, 80.7%, and 85.5% in resting tremor, 70.2%, 79.5%, and 81% in postural tremor, and 60.0%, 58.7%, and 65.0% in kinetic tremor in the index finger MCP joint, the thumb MCP joint, and the wrist, respectively.

CONCLUSION

This first assessment of a WTSD for people living with Parkinson's disease provides confirmation of the feasibility of the approach. The next step requires a comprehensive validation on a broader population in order to evaluate the performance of the WTSD.

SIGNIFICANCE

This study demonstrates the feasibility of using a WTSD to manage hand and finger tremor. The device enriches the field of upper-limb tremor management, as the first WTSD for multiple joints of the hand.

Solvent exposed occupations and risk of Parkinson disease in Finland

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Finnish register-based case-control Parkinson disease (PD) studies are feasible.

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Some occupations with potential for exposure to solvents are associated with PD.

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Chlorinated hydrocarbon solvents in particular might increase PD risk modestly.

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Some occupational co-exposures might enhance PD-solvent associations in PD studies.

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Studies without smoking/education data will underestimate PD-solvent associations.

Introduction

Epidemiologic and toxicology studies suggest that exposure to various solvents, especially chlorinated hydrocarbon solvents, might increase Parkinson disease (PD) risk.

Methods

In a population-based case-control study in Finland, we examined whether occupations with potential for solvent exposures were associated with PD. We identified newly diagnosed cases age 45–84 from a nationwide medication reimbursement register in 1995–2014. From the population register, we randomly selected non-PD controls matched on sex, along with birth and diagnosis years (age). We included 11,757 cases and 23,236 controls with an occupation in the 1990 census, corresponding to age 40–60. We focused on 28 occupations with ≥ 5% probability of solvent exposure according to the Finnish Job Exposure Matrix. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) by logistic regression modeling, adjusting for age, sex, socioeconomic status, and smoking probability.

Results

Similar proportions of cases (5.5%) and controls (5.6%) had an occupation with potential exposure to any solvents. However, all occupations with a point estimate above one, and all significantly or marginally significantly associated with PD (electronic/telecommunications worker [OR = 1.63, 95% CI 1.05–2.50], laboratory assistant [OR = 1.40, 95% CI 0.98–1.99], and machine/engine mechanic [OR = 1.23, 95% CI 0.99–1.52]) entailed potential for exposure to chlorinated hydrocarbon solvents, specifically. Secondary analyses indicated exposure to polycyclic aromatic hydrocarbons and some metals might contribute to the association for mechanics.

Conclusion

PD risk might be slightly increased in occupations with potential exposure to chlorinated hydrocarbon solvents. Confirmation is required in additional studies that adjust for other occupational exposures and smoking.

Does glitazone treatment have a role on the prevention of Parkinson's disease in adult diabetic population? A systematic review

Lately, focus on the relation between Parkinson's disease (PD) and Diabetes has risen greatly, as neuroprotective properties have been attributed to insulin use. Several studies have assessed the effect of glitazones, an insulin-sensitizing agent, in diabetic population on PD future risk. However, reports on the effect of their use have been heterogeneous. We aimed to synthesize the available scientific evidence which assesses the effect of glitazone use in type 2 diabetes patients on PD incidence. A systematic review was performed on multiple electronic databases. Considered for inclusion were studies that assessed the incidence of PD in type 2 diabetes glitazone users. Two reviewers worked independently and in duplicate to assess all studies, extract information and assess the methodological quality in each included study. Four high quality retrospective cohorts fulfilled inclusion criteria. Comparison groups varied across studies. In each study, incidence of PD was lower in glitazone-exposed patients compared to their respective comparison group. Pooled analysis showed lesser risk of PD in ever versus never glitazone users (RR 0.75 [95% C.I. 0.67-0.85; p < .0001; I² = 0]). Our pooled analysis showed lesser risk of PD in glitazone versus non glitazone users, however, we advise to take results with caution since results are non-adjusted to possible confounding variables, furthermore, different glitazone-exposure time, follow up and comparison groups are aspects that also need to be pointed out. More clinical research focused on glitazone use and its relation with PD is needed, as this could result in new potential treatment modalities.

Parkinson's Disease in Women and Men: What's the Difference?

Increasing evidence points to biological sex as an important factor in the development and phenotypical expression of Parkinson’s disease (PD). Risk of developing PD is twice as high in men than women, but women have a higher mortality rate and faster progression of the disease. Moreover, motor and nonmotor symptoms, response to treatments and disease risk factors differ between women and men. Altogether, sex-related differences in PD support the idea that disease development might involve distinct pathogenic mechanisms (or the same mechanism but in a different way) in male and female patients. This review summarizes the most recent knowledge concerning differences between women and men in PD clinical features, risk factors, response to treatments and mechanisms underlying the disease pathophysiology. Unraveling how the pathology differently affect the two sexes might allow the development of tailored interventions and the design of innovative programs that meet the distinct needs of men and women, improving patient care.

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.

Are rises in Electro-Magnetic Field in the human environment, interacting with multiple environmental pollutions, the tripping point for increases in neurological deaths in the Western World?

Whilst humans evolved in the earth's Electro-Magnetic-Field (EMF) and sun-light, both being essential to life but too much sun and we burn. What happens if background EMF rise to critical levels, coinciding with increasing environmental pollutants? Two of the authors can look back over 50 clinical years and appreciate the profound changes in human morbidity across a range of disparate conditions - autoimmune diseases, asthma, earlier cancer incidence and reduced male sperm counts. In particular have been increased autism, dyslexia, Attention Deficit Hyperactivity Disorder and neurological diseases, such as Amyotrophic Lateral Sclerosis, Multiple Sclerosis, Parkinson's Disease, Early Onset Dementia, Multiple System Atrophy and Progressive Supranuclear Palsy. What might have caused these changes-whilst genetic factors are taken as given, multiple environmental pollutants are associated with neurological disease although the mechanisms are unclear. The pace of increased neurological deaths far exceeds any Gompertzian explanation - that because people are living longer they are more likely to develop more age-related problems such as neurological disease. Using WHO global mortality categories of Neurological Disease Deaths (NDD) and Alzheimer's and Dementia deaths (Alz), updated June 2018, together they constitute Total Neurological Mortality (TNM), to calculate mortality rates per million for people aged 55-74 and for the over-75's in twenty-one Western countries. Recent increases in American people aged over-75's rose 49% from 1989 to 2015 but US neurological deaths increased five-fold. In 1989 based on Age-Standardised-Deaths-Rates America USA was 17th at 324 pm but rising to 539 pm became second highest. Different environmental/occupational factors have been found to be associated with neuro-degenerative diseases, including background EMF. We briefly explore how levels of EMF interact upon the human body, which can be described as a natural antennae and provide new evidence that builds upon earlier research to propose the following hypothesis. Based upon recent and new evidence we hypothesise that a major contribution for the relative sudden upsurge in neurological morbidity in the Western world (1989-2015), is because of increased background EMF that has become the tipping point-impacting upon any genetic predisposition, increasing multiple-interactive pollutants, such as rises in petro-chemicals, hormone disrupting chemicals, industrial, agricultural and domestic chemicals. The unprecedented neurological death rates, all within just twenty-five years, demand a re-examination of long-term EMF safety related to the increasing background EMF on human health. We do not wish to 'stop the modern world', only make it safer.

Association of Parkinson's disease with industry sectors: a French nationwide incidence study

In order to identify working environments at risk for Parkinson's disease (PD), we investigated the relation between the importance of industry sectors, used as a surrogate for occupational exposures, and PD incidence in French cantons. The number of incident PD cases (2010-2014) in 3689 cantons of metropolitan France was determined using drug claims from French National Health Insurance databases. The proportions of workers in 38 industry sectors in 2006 were calculated for each canton. Associations between the proportions of workers in industry sectors and PD age/sex-standardized incidence ratios were examined using incidence rate ratios (IRR) and 95% confidence intervals (CI) estimated with multilevel negative binomial regressions with a random intercept at the canton-level and adjusted for smoking, deprivation index, and density of neurologists. We then used two-step semi-Bayes hierarchical regression (HR) to include prior information about exposure to pesticides, metals, and solvents in each industry sector. We identified 112,625 incident cases. PD incidence was higher in areas characterized by high proportions of workers in "Agriculture, forestry and fishing" (IRR_HR = 1.042; CI 95% = 1.014-1.070; p-Trend_HR = 0.004), "Manufacture of textiles, wearing apparel, leather and related products" (IRR_HR = 1.024; CI 95% = 1.005-1.044; p-Trend_HR = 0.010), and "Manufacture of basic metals and fabricated metal products, except machinery and equipment" (IRR_HR = 1.024; CI 95% = 1.003-1.046; p-Trend_HR = 0.071). This nationwide study, based on a comprehensive analysis of industry sectors, shows significant associations between high proportions of workers in specific industry sectors (agriculture, metallurgy, textile) and PD incidence that may be targeted in further epidemiological studies to replicate and better understand these associations.

Clinical and Phenomenological Characteristics of Patients with Task-Specific Lingual Dystonia: Possible Association with Occupation

BACKGROUND

Lingual dystonia is a subtype of oromandibular dystonia, which is a movement disorder characterized by involuntary sustained or intermittent contraction of the masticatory and/or tongue muscles. Lingual dystonia interferes with important daily activities, such as speaking, chewing, and swallowing, resulting in vocational and social disability.

OBJECTIVE

The aim of this study was to investigate a possible relationship between occupation and the development of lingual dystonia.

METHODS

Phenomenological and clinical characteristics of 95 patients [53 females (55.8%) and 42 males (44.2%), mean age 48.0 years] with task-specific, speech-induced lingual dystonia were analyzed. Structured interviews were carried out to obtain information regarding primary occupation, including overtime work and stress during work. The factors that might have influenced the development of lingual dystonia were estimated using multivariate logistic regression analysis of the 95 patients with lingual dystonia and 95 controls [68 females (71.6%) and 27 males (28.4%), mean age 47.2 years] with temporomandibular disorders.

RESULTS

Overall, 84.2% of the patients had regular occupations; 73.8% of the patients with regular occupations reported working overtime more than twice a week, and 63.8% of them experienced stress at the workplace. Furthermore, 82.1% of the patients had engaged in occupations that required them to talk to customers or other people under stressful situations over prolonged periods of time for many years (mean: 15.6 years). The most common occupation was sales representative (17.9%), followed by telephone operator (13.7%), customer service representative (10.5%), health care worker (9.5%), waiter or waitress (5.3%), receptionist (5.3%), and cashier (5.3%). Twenty-nine patients (30.5%) had tardive lingual dystonia. Logistic regression analyses revealed that frequent requirements for professional speaking (p = 0.011, odds ratio: 5.66), high stress during work (p = 0.043, odds ratio: 5.4), and neuroleptic use (p = 0.032, odds ratio: 2.52) were significant contributors to the manifestation of lingual dystonia.

CONCLUSION

Professions in which conversations in stressful situations are unavoidable may trigger lingual dystonia. Therefore, speech-induced lingual dystonia can be regarded as occupational dystonia in certain cases.

Benefits, pitfalls, and future design of population-based registers in neurodegenerative disease

Population-based disease registers identify and characterize all cases of disease, including those that might otherwise be neglected. Prospective population-based registers in neurodegeneration are necessary to provide comprehensive data on the whole phenotypic spectrum and can guide planning of health services. With the exception of the rare disease amyotrophic lateral sclerosis, few complete population-based registers exist for neurodegenerative conditions. Incomplete ascertainment, limitations and uncertainty in diagnostic categorization, and failure to recognize sources of bias reduce the accuracy and usefulness of many registers. Common biases include population stratification, the use of prevalent rather than incident cases in earlier years, changes in disease understanding and diagnostic criteria, and changing demographics over time. Future registers are at risk of funding shortfalls and changes to privacy legislation. Notwithstanding, as heterogeneities of clinical phenotype and disease pathogenesis are increasingly recognized in the neurodegenerations, well-designed longitudinal population-based disease registers will be an essential requirement to complete clinical understanding of neurodegenerative diseases.