Gene-Environment Interactions for Parkinson's Disease

The centenarian blueprint: lessons in defying Parkinson's disease

Recent advancements in neurology have shifted focus from mere diagnosis to comprehensive management of movement disorders, particularly Parkinson's Disease (PD), which is rapidly increasing in prevalence due to global ageing trends. While age is a key risk factor for PD, centenarians often exhibit a remarkably low prevalence of the disease, presenting an intriguing paradox. This viewpoint explores potential reasons for this low prevalence, drawing on studies from regions with high centenarian populations, known as Blue Zones. The authors highlight the importance of genetic, lifestyle, and environmental factors in promoting healthy ageing and examines how these may contribute to the resilience against PD found in centenarians. By understanding the protective mechanisms in centenarians, particularly the concept of hormesis and factors like diet, exercise, and social connections, we may inform prevention strategies for PD. The study proposes the "EAT, MOVE, SLEEP, PROTECT, and REPEAT" approach as a framework for lifestyle interventions to counteract PD risk factors. Ultimately, centenarians offer valuable insights into delaying neurodegeneration, providing a model for potential preventive trials for PD.

Filipinos and Parkinson's disease: A scoping review of the literature

BACKGROUND

Filipinos are the third largest sub-group of Asian Americans in the United States and have greater socioeconomic and health disparities than many other Asian sub-groups [1,2,3,4,5,6,7,8]. Characteristics of Filipino patients with Parkinson's disease (PD) have not been adequately studied.

OBJECTIVE

To scope the extent, range and nature of current knowledge on PD in Filipino-American (FA) patients in contrast to Filipino patients in general.

METHODS

We undertook a scoping review including all types of research relating to PD in Filipinos. We searched the following electronic databases: MEDLINE via PubMed, Google Scholar, Cochrane Library, Herdin and Journals@OVID (searched 1944-November 2024). Criteria for inclusion were peer-reviewed empirical articles published in English that specifically included and described Filipino patients with PD. We reviewed all eligible articles and categorized them by general topical themes.

RESULTS

The scoping review resulted in 48 eligible papers (Fig. 1). There were 7 papers that discussed PD in FA, and 35 papers that discussed PD in the Philippines. The main themes identified from the scoping review were: epidemiology/etiology (n = 19, 39 %), clinical manifestations and management (n = 20, 42 %), and access to PD care (n = 9, 19 %).

CONCLUSION

There is a paucity of information on PD in the FA population, with the majority of studies from the Philippines. Further studies on FA in the US, when compared to the studies from the Philippines, may shed light on how differences in the environment and sociodemographic factors may influence the nature and course of PD.

Pelargonium graveolens Attenuates Rotenone-Induced Parkinson's Disease in a Rat Model: Role of MAO-B Inhibition and In Silico Study

Parkinson's disease (PD), the second most common neurodegenerative condition, is primarily characterized by motor dysfunctions due to dopaminergic neuronal loss in the Substantia Nigra (SN), with oxidative stress playing a significant role in its progression. This study investigates the neuroprotective potential of Pelargonium graveolens (Thunb.) L'Hér leaves in a rotenone-induced PD rat model. The total ethanolic extract and its fractions, obtained via Diaion HP-20 column chromatography, were evaluated for monoamine oxidase-B (MAO-B) inhibition in vitro. The 50% methanol fraction (PG50) demonstrated the highest MAO-B inhibition (IC50 5.26 ± 0.12 µg/ml) compared to the reference drug selegiline (IC50 0.021 ± 0.003 µg/ml). In a rotenone-induced PD rat model, PG50 (100 mg/kg, p.o.) alleviated motor deficits (assessed via the wire hanging test), and restored norepinephrine, dopamine, and serotonin levels. PG50 and L-dopa reduced α-synuclein levels by 367.60% and 377.48%, respectively. Oxidative balance was restored with increased glutathione (23.12%) and decreased malondialdehyde (164.19%) in brain tissues. PG50 significantly reduced serum TNF-α (572.79%) and IL-6 (70.84%) levels, and improved succinate dehydrogenase (14.47%) and lactate dehydrogenase (7.74%) activities in brain tissues. Histopathological alterations in the SN were also ceased. UPLC-MS/MS analysis identified 61 metabolites, including 32 flavonoids, 13 phenolic acids, 7 coumarins, 5 phenolic glycosides, and 4 dicarboxylic acids, with in silico docking showing strong MAO-B binding by methoxylated flavonoids like methoxyluteolin dimethyl ether (docking score: - 8.0625 kcal/mol), surpassing that of safinamide (- 8.2615 kcal/mol). These findings suggest that P. graveolens holds promise as a neuroprotective agent against rotenone-induced PD.

Environmental Risk Factors for Parkinson's Disease: A Critical Review and Policy Implications

The age-standardized prevalence of Parkinson's disease (PD) has increased substantially over the years and is expected to increase further. This emphasizes the need to identify modifiable risk factors of PD, which could form a logical entry point for the prevention of PD. The World Health Organization (WHO) has recommended reducing exposure to specific environmental factors that have been reported to be associated with PD, in particular pesticides, trichloroethylene (TCE), and air pollution. In this review we critically evaluate the epidemiological and biological evidence on the associations of these factors with PD and review evidence on whether these putative associations are causal. We conclude that when considered in isolation, it is difficult to determine whether these associations are causal, in large part because of the decades-long lag between relevant exposures and the incidence of manifest PD. However, when considered in tandem with evidence from complementary research lines (such as animal models), it is increasingly likely that these associations reflect harmful causal effects. Fundamentally, whilst we highlight some evidence gaps that require further attention, we believe the current evidence base is sufficiently strong enough to support our call for stronger policy action. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Nanotechnology in Parkinson's Disease: overcoming drug delivery challenges and enhancing therapeutic outcomes

The global prevalence of Parkinson's Disease (PD) is on the rise, driven by an ageing population and ongoing environmental conditions. To gain a better understanding of PD pathogenesis, it is essential to consider its relationship with the ageing process, as ageing stands out as the most significant risk factor for this neurodegenerative condition. PD risk factors encompass genetic predisposition, exposure to environmental toxins, and lifestyle influences, collectively increasing the chance of PD development. Moreover, early and precise PD diagnosis remains elusive, relying on clinical assessments, neuroimaging techniques, and emerging biomarkers. Conventional management of PD involves dopaminergic medications and surgical interventions, but these treatments often become less effective over time and do not address disease treatment. Challenges persist due to the blood-brain barrier's (BBB) impermeability, hindering drug delivery. Recent advancements in nanotechnology offer promising novel approaches for PD management. Various drug delivery systems (DDS), including nanosized polymers, lipid-based carriers, and nanoparticles (such as metal/metal oxide, protein, and carbonaceous particles), aim to enhance drug and gene delivery. These modifications seek to improve BBB permeability, ultimately benefiting PD patients. This review underscores the critical role of ageing in PD development and explores how age-related neuronal decline contributes to substantia nigra loss and PD manifestation in susceptible individuals. The review also highlights the advancements and ongoing challenges in nanotechnology-based therapies for PD.

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.

Caffeine Consumption and Interaction with ADORA2A, CYP1A2 and NOS1 Variants Do Not Influence Age at Onset of Machado-Joseph Disease

BACKGROUND

The age at onset (AO) of Machado-Joseph disease (SCA3/MJD), a disorder due to an expanded CAG repeat (CAGexp) in ATXN3, is quite variable and the role of environmental factors is still unknown. Caffeine was associated with protective effects against other neurodegenerative diseases, and against SCA3/MJD in transgenic mouse models. We aimed to evaluate whether caffeine consumption and its interaction with variants of caffeine signaling/metabolization genes impact the AO of this disease.

METHODS

a questionnaire on caffeine consumption was applied to adult patients and unrelated controls living in Rio Grande do Sul, Brazil. AO and CAGexp were previously determined. SNPs rs5751876 (ADORA2A), rs2298383 (ADORA2A), rs762551 (CYP1A2) and rs478597 (NOS1) were genotyped. AO of subgroups were compared, adjusting the CAGexp to 75 repeats (p < 0.05).

RESULTS

171/179 cases and 98/100 controls consumed caffeine. Cases with high and low caffeine consumption (more or less than 314.5 mg of caffeine/day) had mean (SD) AO of 35.05 (11.44) and 35.43 (10.08) years (p = 0.40). The mean (SD) AO of the subgroups produced by the presence or absence of caffeine-enhancing alleles in ADORA2A (T allele at rs5751876 and rs2298383), CYP1A2 (C allele) and NOS1 (C allele) were all similar (p between 0.069 and 0.516).

DISCUSSION

Caffeine consumption was not related to changes in the AO of SCA3/MJD, either alone or in interaction with protective genotypes at ADORA2A, CYP1A2 and NOS1.

The combined effect of lifestyle factors and polygenic scores on age at onset in Parkinson's disease

The objective of this study was to investigate the association between a Parkinson's disease (PD)-specific polygenic score (PGS) and protective lifestyle factors on age at onset (AAO) in PD. We included data from 4367 patients with idiopathic PD, 159 patients with GBA1-PD, and 3090 healthy controls of European ancestry from AMP-PD, PPMI, and Fox Insight cohorts. The association between PGS and lifestyle factors on AAO was assessed with linear and Cox proportional hazards models. The PGS showed a negative association with AAO (β = - 1.07, p = 6 × 10-7) in patients with idiopathic PD. The use of one, two, or three of the protective lifestyle factors showed a reduction in the hazard ratio by 21% (p = 0.0001), 44% (p < 2 × 10-16), and 55% (p < 2 × 10-16), compared to no use. An additive effect of aspirin (β = 7.62, p = 9 × 10-7) and PGS (β = - 1.58, p = 0.0149) was found for AAO without an interaction (p = 0.9993) in the linear regressions, and similar effects were seen for tobacco. In contrast, no association between aspirin intake and AAO was found in GBA1-PD (p > 0.05). In our cohort, coffee, tobacco, aspirin, and PGS are independent predictors of PD AAO. Additionally, lifestyle factors seem to have a greater influence on AAO than common genetic risk variants with aspirin presenting the largest effect.

The rise of Parkinson's disease is a global challenge, but efforts to tackle this must begin at a national level: a protocol for national digital screening and "eat, move, sleep" lifestyle interventions to prevent or slow the rise of non-communicable diseases in Thailand

The rising prevalence of Parkinson's disease (PD) globally presents a significant public health challenge for national healthcare systems, particularly in low-to-middle income countries, such as Thailand, which may have insufficient resources to meet these escalating healthcare needs. There are also many undiagnosed cases of early-stage PD, a period when therapeutic interventions would have the most value and least cost. The traditional "passive" approach, whereby clinicians wait for patients with symptomatic PD to seek treatment, is inadequate. Proactive, early identification of PD will allow timely therapeutic interventions, and digital health technologies can be scaled up in the identification and early diagnosis of cases. The Parkinson's disease risk survey (TCTR20231025005) aims to evaluate a digital population screening platform to identify undiagnosed PD cases in the Thai population. Recognizing the long prodromal phase of PD, the target demographic for screening is people aged ≥ 40 years, approximately 20 years before the usual emergence of motor symptoms. Thailand has a highly rated healthcare system with an established universal healthcare program for citizens, making it ideal for deploying a national screening program using digital technology. Designed by a multidisciplinary group of PD experts, the digital platform comprises a 20-item questionnaire about PD symptoms along with objective tests of eight digital markers: voice vowel, voice sentences, resting and postural tremor, alternate finger tapping, a "pinch-to-size" test, gait and balance, with performance recorded using a mobile application and smartphone's sensors. Machine learning tools use the collected data to identify subjects at risk of developing, or with early signs of, PD. This article describes the selection and validation of questionnaire items and digital markers, with results showing the chosen parameters and data analysis methods to be robust, reliable, and reproducible. This digital platform could serve as a model for similar screening strategies for other non-communicable diseases in Thailand.

Towards a Global View of Parkinson's Disease Genetics

Parkinson's disease (PD) is a global health challenge, yet historically studies of PD have taken place predominantly in European populations. Recent genetics research conducted in non-European populations has revealed novel population-specific genetic loci linked to PD risk, highlighting the importance of studying PD globally. These insights have broadened our understanding of PD etiology, which is crucial for developing disease-modifying interventions. This review comprehensively explores the global genetic landscape of PD, emphasizing the scientific rationale for studying underrepresented populations. It underscores challenges, such as genotype-phenotype heterogeneity and inclusion difficulties for non-European participants, emphasizing the ongoing need for diverse and inclusive research in PD. ANN NEUROL 2024;95:831-842.

Occupational Pesticide Exposure in Parkinson's Disease Related to GBA and LRRK2 Variants

Background

The penetrance of common genetic risk variants for Parkinson's disease (PD) is low. Pesticide exposure increases PD risk, but how exposure affects penetrance is not well understood.

Objective

To determine the relationship between occupational pesticide exposure and PD in people with LRRK2 and GBA risk variants.

Methods

Participants of the Parkinson's Progression Markers Initiative (PPMI) with a LRRK2-G2019 S or GBA risk variant provided information about occupational pesticide exposure. We compared exposure in carriers with and without PD. Among carriers with PD, we used Cox proportional hazard models to compare time-to impairment in balance, cognition, and activities of daily living (ADLs) between participants with and without prior occupational pesticide exposure.

Results

378 participants with a risk variant provided exposure information; 176 with LRRK2-G2019 S (54 with and 122 without PD) and 202 with GBA variants (47 with and 155 without PD). Twenty-six participants reported pesticide exposure. People with a GBA variant and occupational pesticide exposure had much higher odds of PD (aOR: 5.4, 95% CI 1.7-18.5, p < 0.01). People with a LRRK2 variant and a history of occupational pesticide exposure had non-significantly elevated odds of PD (aOR 1.3, 95% CI 0.4-4.6, p = 0.7). Among those with PD, pesticide exposure was associated with a higher risk of balance problems and cognitive impairment in LRRK2-PD and functional impairment in GBA-PD, although associations were not statistically significant.

Conclusions

Occupational pesticide exposure may increase penetrance of GBA-PD and may be associated with faster symptom progression. Further studies in larger cohorts are necessary.

Parkinson's Disease is Predominantly a Genetic Disease

The discovery of a pathogenic variant in the alpha-synuclein (SNCA) gene in the Contursi kindred in 1997 indisputably confirmed a genetic cause in a subset of Parkinson's disease (PD) patients. Currently, pathogenic variants in one of the seven established PD genes or the strongest known risk factor gene, GBA1, are identified in ∼15% of PD patients unselected for age at onset and family history. In this Debate article, we highlight multiple avenues of research that suggest an important - and in some cases even predominant - role for genetics in PD aetiology, including familial clustering, high rates of monogenic PD in selected populations, and complete penetrance with certain forms. At first sight, the steep increase in PD prevalence exceeding that of other neurodegenerative diseases may argue against a predominant genetic etiology. Notably, the principal genetic contribution in PD is conferred by pathogenic variants in LRRK2 and GBA1 and, in both cases, characterized by an overall late age of onset and age-related penetrance. In addition, polygenic risk plays a considerable role in PD. However, it is likely that, in the majority of PD patients, a complex interplay of aging, genetic, environmental, and epigenetic factors leads to disease development.