Environmental Risk Factors For Parkinson's Disease Research Articles

Lifestyle Factors and Parkinson's Disease Risk in a Rural New England Case-Control Study.

Introduction Parkinson's disease (PD) is an age-related neurodegenerative disease likely caused by complex interactions between genetic and environmental risk factors. Exposure to pesticides, toxic metals, solvents, and history of traumatic brain injury have been implicated as environmental risk factors for PD, underscoring the importance of identifying risk factors associated with PD across different communities. Methods We conducted a questionnaire-based case-control study in a rural area on the New Hampshire/Vermont border, enrolling PD patients and age- and sex-matched controls from the general population between 2017 and 2020. We assessed frequent participation in a variety of recreational and occupational activities and surveyed potential chemical exposures. Results Suffering from “head trauma or a concussion” prior to diagnosis was associated with a fourfold increased risk of PD. Adjustment for head trauma negated any risk of participation in “strenuous athletic activities.” We observed a 2.7-fold increased risk of PD associated with activities involving lead (adjusted p=0.038). Conclusion Implicating these factors in PD risk favors public health efforts in exposure mitigation while also motivating future work mechanisms and intervention opportunities.

ATP13A2-mediated endo-lysosomal polyamine export counters mitochondrial oxidative stress

Recessive loss-of-function mutations in ATP13A2 (PARK9) are associated with a spectrum of neurodegenerative disorders, including Parkinson's disease (PD). We recently revealed that the late endo-lysosomal transporter ATP13A2 pumps polyamines like spermine into the cytosol, whereas ATP13A2 dysfunction causes lysosomal polyamine accumulation and rupture. Here, we investigate how ATP13A2 provides protection against mitochondrial toxins such as rotenone, an environmental PD risk factor. Rotenone promoted mitochondrial-generated superoxide (MitoROS), which was exacerbated by ATP13A2 deficiency in SH-SY5Y cells and patient-derived fibroblasts, disturbing mitochondrial functionality and inducing toxicity and cell death. Moreover, ATP13A2 knockdown induced an ATF4-CHOP-dependent stress response following rotenone exposure. MitoROS and ATF4-CHOP were blocked by MitoTEMPO, a mitochondrial antioxidant, suggesting that the impact of ATP13A2 on MitoROS may relate to the antioxidant properties of spermine. Pharmacological inhibition of intracellular polyamine synthesis with α-difluoromethylornithine (DFMO) also increased MitoROS and ATF4 when ATP13A2 was deficient. The polyamine transport activity of ATP13A2 was required for lowering rotenone/DFMO-induced MitoROS, whereas exogenous spermine quenched rotenone-induced MitoROS via ATP13A2. Interestingly, fluorescently labeled spermine uptake in the mitochondria dropped as a consequence of ATP13A2 transport deficiency. Our cellular observations were recapitulated in vivo, in a Caenorhabditis elegans strain deficient in the ATP13A2 ortholog catp-6 These animals exhibited a basal elevated MitoROS level, mitochondrial dysfunction, and enhanced stress response regulated by atfs-1, the C. elegans ortholog of ATF4, causing hypersensitivity to rotenone, which was reversible with MitoTEMPO. Together, our study reveals a conserved cell protective pathway that counters mitochondrial oxidative stress via ATP13A2-mediated lysosomal spermine export.

Time trends in the prevalence and incidence of Parkinson's disease in Taiwan: A nationwide, population-based study.

Identifying trends in the prevalence and incidence of Parkinson's disease (PD) may yield information that supports public health goals. Our aim was to evaluate time-trend changes in the prevalence and incidence of PD in Taiwan between 2004 and 2011. This retrospective, nationwide, longitudinal study used the Taiwan National Health Insurance Research Database to identify patients with PD from 2004 to 2011 based on having ICD-9-CM diagnostic codes, which were assigned by neurologists, and being prescribed PD medication. Annual incidence and prevalence were calculated, and time-trend analyses were estimated assuming a Poisson distribution. Over the study period, 19,302 patients in 2004 and 41,606 patients in 2011 fulfilling the study criteria for PD were included in the analysis. The average age-standardized prevalence of PD per 100,000 of population was 84.8 in 2004 and 147.7 in 2011, with a 7.9% yearly increase. Increasing prevalence trends of PD were statistically significant (p<0.001) in all age groups, with the steepest rate among those aged≥80 years. In contrast, the average age-standardized incidence of PD decreased steadily from 35.3 per 100,000 in 2005 to 28.8 per 100,000 in 2011. The incidence rate was higher in men than in women, and increased with age. We identified an increasing trend in the annual prevalence rates of PD from 2004 to 2011; however, the substantial decline in the incidence of PD suggests that some major environmental risk factors for PD were removed from this population during this time period.

Selective damage to dopaminergic transporters following exposure to the brominated flame retardant, HBCDD

Over the last several decades, the use of halogenated organic compounds has become the cause of environmental and human health concerns. Of particular notoriety has been the establishment of the neurotoxicity of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). The subsequent banning of PBDEs has led to greatly increased use of 1,2,5,6,9,10-hexabromocyclododecane (HBCDD, also known as HBCD) as a flame retardant in consumer products. The physiochemical similarities between HBCDD and PBDEs suggest that HBCDD may also be neurotoxic to the dopamine system, which is specifically damaged in Parkinson disease (PD). The purpose of this study was to assess the neurotoxicity of HBCDD on the nigrostriatal dopamine system using an in vitro and in vivo approach. We demonstrate that exposure to HBCDD (0–25μM) for 24h causes significant cell death in the SK-N-SH catecholaminergic cell line, as well as reductions in the growth and viability of TH+ primary cultured neurons at lower concentrations (0–10μM) after 72h of treatment. Assessment of the in vivo neurotoxicity of HBCDD (25mg/kg for 30days) resulted in significant reductions in the expression of the striatal dopamine transporter and vesicular monoamine transporter 2, both of which are integral in mediating dopamine homeostasis and neurotransmission in the dopamine circuit. However, no changes were seen in the expression of tyrosine hydroxylase in the dopamine terminal, or striatal levels of dopamine. To date, these are the first data to demonstrate that exposure to HBCDD disrupts the nigrostriatal dopamine system. Given these results and the ubiquitous nature of HBCDD in the environment, its possible role as an environmental risk factor for PD should be further investigated.

Fenpropathrin, a Widely Used Pesticide, Causes Dopaminergic Degeneration.

Fenpropathrin is one of the widely used pyrethroids in agriculture and household and also reported to have neurotoxic effects in rodent models. In our Parkinson's disease (PD) clinic, there was a unique patient with a history of daily exposure to fenpropathrin for 6 months prior to developing Parkinsonian symptoms progressively. Since whether fenpropathrin is related to any dopaminergic degeneration was unknown, we aimed in this study to evaluate the neurotoxic effects of fenpropathrin on the dopaminergic system and associated mechanisms in vitro and in vivo. In cultured SH-SY5Y cells, fenpropathrin caused cell death, reactive oxygen species generation, Lewy body-associated proteins aggregation, and Lewy body-like intracytoplasmic inclusions formation. In rodent animals, two different injections of fenpropathrin were used for administrations, intraperitoneal (i.p), or stereotaxical (ST). The rats exhibited lower number of pokes 60 days after first i.p injection, while the rats in ST group showed a significant upregulation of apomorphine-evoked rotations 60 days after first injection. Decreased tyrosine hydroxylase (TH) and vesicular monoamine transporter 2 (VMAT2) immunoreactivity, while increased dopamine transporter (DAT) immunoreactivity were observed in rats of either i.p or ST group 60 days after the last exposure to fenpropathrin. However, the number of TH-positive cells in the substantia nigra was more reduced 120 days after the first i.p injection than those of 60 days. Our data demonstrated that exposure to fenpropathrin could mimic the pathologic and pathogenetic features of PD especially in late onset cases. These results imply fenpropathrin as a DA neurotoxin and a possible environmental risk factor for PD.

PARK2 patient neuroprogenitors show increased mitochondrial sensitivity to copper

Poorly-defined interactions between environmental and genetic risk factors underlie Parkinson's disease (PD) etiology. Here we tested the hypothesis that human stem cell derived forebrain neuroprogenitors from patients with known familial risk for early onset PD will exhibit enhanced sensitivity to PD environmental risk factors compared to healthy control subjects without a family history of PD. Two male siblings (SM and PM) with biallelic loss-of-function mutations in PARK2 were identified. Human induced pluripotent stem cells (hiPSCs) from SM, PM, and four control subjects with no known family histories of PD or related neurodegenerative diseases were utilized. We tested the hypothesis that hiPSC-derived neuroprogenitors from patients with PARK2 mutations would show heightened cell death, mitochondrial dysfunction, and reactive oxygen species generation compared to control cells as a result of exposure to heavy metals (PD environmental risk factors). We report that PARK2 mutant neuroprogenitors showed increased cytotoxicity with copper (Cu) and cadmium (Cd) exposure but not manganese (Mn) or methyl mercury (MeHg) relative to control neuroprogenitors. PARK2 mutant neuroprogenitors also showed a substantial increase in mitochondrial fragmentation, initial ROS generation, and loss of mitochondrial membrane potential following Cu exposure. Our data substantiate Cu exposure as an environmental risk factor for PD. Furthermore, we report a shift in the lowest observable effect level (LOEL) for greater sensitivity to Cu-dependent mitochondrial dysfunction in patients SM and PM relative to controls, correlating with their increased genetic risk for PD.

Dopaminergic neurotoxicity ofS‐ethylN,N‐dipropylthiocarbamate (EPTC), molinate, andS‐methyl‐N,N‐diethylthiocarbamate (MeDETC) inCaenorhabditis elegans

Epidemiological studies corroborate a correlation between pesticide use and Parkinson's disease (PD). Thiocarbamate and dithiocarbamate pesticides are widely used and produce neurotoxicity in the peripheral nervous system. Recent evidence from rodent studies suggests that these compounds also cause dopaminergic (DAergic) dysfunction and altered protein processing, two hallmarks of PD. However, DAergic neurotoxicity has yet to be documented. We assessed DAergic dysfunction in Caenorhabditis elegans (C. elegans) to investigate the ability of thiocarbamate pesticides to induce DAergic neurodegeneration. Acute treatment with either S-ethyl N,N-dipropylthiocarbamate (EPTC), molinate, or a common reactive intermediate of dithiocarbamate and thiocarbamate metabolism, S-methyl-N,N-diethylthiocarbamate (MeDETC), to gradual loss of DAergic cell morphology and structure over the course of 6 days in worms expressing green fluorescent protein (GFP) under a DAergic cell specific promoter. HPLC analysis revealed decreased DA content in the worms immediately following exposure to MeDETC, EPTC, and molinate. In addition, worms treated with the three test compounds showed a drastic loss of DAergic-dependent behavior over a time course similar to changes in DAergic cell morphology. Alterations in the DAergic system were specific, as loss of cell structure and neurotransmitter content was not observed in cholinergic, glutamatergic, or GABAergic systems. Overall, our data suggest that thiocarbamate pesticides promote neurodegeneration and DAergic cell dysfunction in C. elegans, and may be an environmental risk factor for PD.

Genetic susceptibility loci, environmental exposures, and Parkinson's disease: A case–control study of gene–environment interactions

BackgroundPrior studies causally linked mutations in SNCA, MAPT, and LRRK2 genes with familial Parkinsonism. Genome-wide association studies have demonstrated association of single nucleotide polymorphisms (SNPs) in those three genes with sporadic Parkinson's disease (PD) susceptibility worldwide. Here we investigated the interactions between SNPs in those three susceptibility genes and environmental exposures (pesticides application, tobacco smoking, coffee drinking, and alcohol drinking) also associated with PD susceptibility. MethodsPairwise interactions between environmental exposures and 18 variants (16 SNPs and two variable number tandem repeats, or “VNTRs”) in SNCA, MAPT and LRRK2, were investigated using data from 1098 PD cases from the upper Midwest, USA and 1098 matched controls. Environmental exposures were assessed using a validated telephone interview script. ResultsFive pairwise interactions had uncorrected P-values < 0.05. These included pairings of pesticides × SNCA rs3775423 or MAPT rs4792891, coffee drinking × MAPT H1/H2 haplotype or MAPT rs16940806, and alcohol drinking × MAPT rs2435211. None of these interactions remained significant after Bonferroni correction. Secondary analyses in strata defined by type of control (sibling or unrelated), sex, or age at onset of the case also did not identify significant interactions after Bonferroni correction. ConclusionsThis study documented limited pairwise interactions between established genetic and environmental risk factors for PD; however, the associations were not significant after correction for multiple testing.

Genetic risk for Parkinson's disease correlates with alterations in neuronal manganese sensitivity between two human subjects

Manganese (Mn) is an environmental risk factor for Parkinson's disease (PD). Recessive inheritance of PARK2 mutations is strongly associated with early onset PD (EOPD). It is widely assumed that the influence of PD environmental risk factors may be enhanced by the presence of PD genetic risk factors in the genetic background of individuals. However, such interactions may be difficult to predict owing to the complexities of genetic and environmental interactions. Here we examine the potential of human induced pluripotent stem (iPS) cell-derived early neural progenitor cells (NPCs) to model differences in Mn neurotoxicity between a control subject (CA) with no known PD genetic risk factors and a subject (SM) with biallelic loss-of-function mutations in PARK2 and family history of PD but no evidence of PD by neurological exam. Human iPS cells were generated from primary dermal fibroblasts of both subjects. We assessed several outcome measures associated with Mn toxicity and PD. No difference in sensitivity to Mn cytotoxicity or mitochondrial fragmentation was observed between SM and CA NPCs. However, we found that Mn exposure was associated with significantly higher reactive oxygen species (ROS) generation in SM compared to CA NPCs despite significantly less intracellular Mn accumulation. Thus, this report offers the first example of human subject-specific differences in PD-relevant environmental health related phenotypes that are consistent with pathogenic interactions between known genetic and environmental risk factors for PD.

An Exploratory Analysis on Gene-Environment Interactions for Parkinson Disease (PD4.003)

Objective: To explore potential interactions between variations of Parkinson disease (PD) susceptibility genes with smoking and caffeine intake. Background Gene-environment interaction is critical to understanding the etiology of PD. Little, however, is known about whether PD susceptibility genes interact with known environmental risk factors for PD. Design/Methods: We examined potential interactions of prospectively collected data on smoking and caffeine intake with several PD susceptible SNPs selected from previous GWAS, among 584 non-Hispanic Caucasian cases and 1,571 controls. Genotyping data were primarily from the replication sample of a previous GWAS study, and we focused on ten tag SNPs at or flanking the SNCA, MAPT, LRRK2 and HLA-DRA loci. Results: The main effects of PD susceptibility loci and environmental exposures were consistent with previous reports. Family history was also associated with PD risk (OR=2.71, 95% CI: 1.97 3.37), which was little affected after further adjusting for these SNPs and environmental exposures. Overall, we did not find significant interactions of either smoking or caffeine intake with these SNPs. However, with a combined smoking and caffeine exposure, we found a significant interaction with rs2896905 near the LRRK2 gene (uncorrected p = 0.0008), which remained statistically significant even after Bonferroni correction. Each A allele was associated with a 35% higher PD risk (OR=1.35, 95% CI: 1.01 – 1.82, p = 0.04) among never smokers with low caffeine intake, but with a 32% lower PD risk (OR=0.68, 95% CI: 0.51 – 0.90, p = 0.007) among smokers with high caffeine intake. Conclusions: This study provides preliminary evidence that smoking and caffeine intake may modify the association of rs2896905 with PD, which should be confirmed and investigated in future studies. Supported by: The intramural research program of the NIH, the National Institute of Environmental Health Sciences (Z01-ES-101986), the National Cancer Institute (Z01 CP010196-02), and a NIH extramural grant (R01 NS060722) to Dr Huang. Disclosure: Dr. Gao has nothing to disclose. Dr. Nalls has nothing to disclose. Dr. Shi has nothing to disclose. Dr. Joubert has nothing to disclose. Dr. Hernandez has nothing to disclose. Dr. Huang has nothing to disclose. Dr. Hollenbeck has nothing to disclose. Dr. Singleton has nothing to disclose. Dr. Chen has nothing to disclose.

Transgenic conversion of omega-6 into omega-3 fatty acids in a mouse model of Parkinson's disease

We have recently identified a neuroprotective role for omega-3 polyunsaturated fatty acids (n-3 PUFAs) in a toxin-induced mouse model of Parkinson's disease (PD). Combined with epidemiological data, these observations suggest that low n-3 PUFA intake is a modifiable environmental risk factor for PD. In order to strengthen these preclinical findings as prerequisite to clinical trials, we further investigated the neuroprotective role of n-3 PUFAs in Fat-1 mice, a transgenic model expressing an n-3 fatty acid desaturase converting n-6 PUFAs into n-3 PUFAs. Here, we report that the expression of the fat-1 transgene increased cortical n-3:n-6 PUFA ratio (+28%), but to a lesser extent than dietary supplementation (92%). Such a limited endogenous production of n-3 PUFAs in the Fat-1 mouse was insufficient to confer neuroprotection against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine neurotoxicity as assessed by dopamine levels, tyrosine hydroxylase (TH)-positive neurons and fibers, as well as nigral Nurr1 and dopamine transporter (DAT) mRNA expression. Nevertheless, higher cortical docosahexaenoic acid (DHA) concentrations were positively correlated with markers of nigral dopaminergic neurons such as the number of TH-positive cells, in addition to Nurr1 and DAT mRNA levels. These associations are consistent with the protective role of DHA in a mouse model of PD. Taken together, these data suggest that dietary intake of a preformed DHA supplement is more effective in reaching the brain and achieving neuroprotection in an animal model of PD.

Joining Forces to Understand Parkinson Disease

Vol. 113, No. 3 AnnouncementsOpen AccessJoining Forces to Understand Parkinson Disease Cindy Lawler Cindy Lawler Search for more papers by this author Published:1 March 2005https://doi.org/10.1289/ehp.113-1253777AboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit Parkinson disease (PD) continues to be a high research priority at the NIEHS. The institute currently supports a broad scope of research, from molecular epidemiology studies of environmental risk and protective factors for PD to basic laboratory investigations aimed at developing new animal models, understanding the role of mitochondrial oxidative damage in vulnerable cell populations, and defining transport mechanisms for toxicant entry to the brain. Taken together, results from these studies provide strong support for the idea that typical late-onset PD reflects joint effects of environmental factors and genetic susceptibility.The NIEHS has special interest in enabling the synthesis of findings emerging across disparate disciplines and research settings in the PD arena. The NIEHS Collaborative Centers for Parkinson’s Disease Environmental Research (CCPDER) Program was initiated in 2002 to strengthen the interchange among geneticists, clinicians, epidemiologists, and scientists engaged in fundamental laboratory research on PD. In June 2004, all NIEHS grantees in the area of neurodegeneration were brought together to share their most recent findings, and to identify and encourage new areas of collaboration among investigators. Most recently, the NIEHS partnered with the National Institute of Neurological Disorders and Stroke to support the development of a database, PD-DOC, that will enable sharing of clinical, pathological, biochemical, and risk factor information among researchers.A high-priority need that has been identified by PD researchers is for improved methodologies to facilitate data pooling, combined analysis, and comparison of results across epidemiologic studies. In response to this need, the NIEHS has provided support through the CCPDER Program for two meetings that will bring together PD epidemiologists and related experts to develop a series of methodologic recommendations. These will include guidelines for ascertainment and case definition in epidemiologic field studies, and recommendations for both exposure assessment methods and a minimal data set of high-importance exposures to be collected in future investigations. Materials produced through this mechanism will be made widely available through venues such as the CCPDER website, and will be used to guide the development of the epidemiologic component of PD-DOC.Collectively, these efforts are intended to improve the ability of epidemiologic researchers to identify novel genetic and environmental risk factors for PD, and to inform and be informed by mechanistic laboratory-based research. Ultimately, these data will provide a basis for devising strategies to prevent disease by avoiding or ameliorating harmful exposures and exploiting those exposures that confer protection.FiguresReferencesRelatedDetails Vol. 113, No. 3 March 2005Metrics About Article Metrics Publication History Originally published1 March 2005Published in print1 March 2005 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. Our staff will work with you to assess and meet your accessibility needs within 3 working days.

Case–control study of environmental risk factors for Parkinson's disease in Belgium

The aetiology of Parkinson's disease (PD) is unknown and said to be multifactorial. We report on a retrospective epidemiological case control study, performed in Flanders during a 3-year period, investigating known and potential environmental risk factors for PD by means of questionnaires. We investigated 423 prevalent patients and 205 spouse-controls. We found familial occurrence in 15% of the patients, a mean age of onset of 58 years, and a clear male preponderance (male/female ratio 1.53). Our results suggest more nulliparity among female PD patients (95% CI: 1.08-5.76). We found a discrete clustering of patients in areas with intensive metallurgic frequently employed in metallurgy than controls (95% CI: 1.04-9.20). Furthermore, patients were clearly more exposed to zinc (95% CI: 1.51-90.90) and toluene (95% CI: 1.03 58.82). Male patients report more prostatectomy-surgery (95% CI: 1.54-17.24).

Platelet mitochondrial respiratory chain function in Parkinson's disease

Reports on mitochondrial respiratory chain (MRC) complex I (CI) dysfunction in the substantia nigra in Parkinson's disease (PD) support the oxidative stress hypothesis in the neuropathogenesis of PD. Studies in peripheral tissue have found variable decreased CI and occasionally other complex activity suggestive of systemic impairment of MRC function in PD; however, MRC activity may be influenced by numerous variables. We conducted spectrophotometric measurements of MRC function in platelet mitochondrial preparations in 13 individuals with PD and 9 age-matched controls (CON) and have identified additional variables that may affect MRC activity. Mean CI, CIII, CIV, and citrate synthase (CS) activities were similar between PD and CON. CIII and CIV, specific and CS-corrected, activities were significantly positively correlated with CI in combined and individual group data, with the exception of CIII CS-corrected and CIV specific activities in CON and PD, respectively. CIII and CS specific activities were negatively correlated with age in CON, but varied randomly in PD. In PD, CIII specific activity was 1.4-fold higher in those with a history of environmental risk factors for PD and CIV specific activity was lower in those with a positive family history of PD [8.34 +/- 0.74 (n = 4) vs. 12.4 +/- 1.1 (SEM) min-1 mg-1; p = 0.046]. Group heterogeneity, variables affecting enzyme activity, and intrinsic properties of cells may thus contribute to conflicting data in studies of MRC function in platelets and other tissues.

Worldwide Occurrence of Parkinson's Disease: An Updated Review

Comparison of Parkinson's disease (PD) prevalence and incidence in various parts of the world is difficult because methods of case ascertainment, diagnostic criteria, classification, medical facilities, and age distribution of the populations vary broadly in different studies. We minimized these differences by adjusting available data to a single standard population. Using this we calculated age-adjusted rates for 27 regional populations and analyzed PD frequency from 45 communities. We conclude: (1) with the exception of China, Japan and Africa, which have the lowest prevalence ratios, the actual prevalence variation for PD is probably lower than previously reported in geographically diverse populations; (2) geographic variation is unlikely to be due exclusively to racial factors, and (3) environmental risk factors for PD might differ regionally.