Is Pesticide Use Related to Parkinson Disease? Some Clues to Heterogeneity in Study Results

Abstract

Background: Previous systematic reviews have indicated that pesticide exposure is possibly associated with Parkinson disease (PD). However, considerable heterogeneity has been observed in study results.Objective: We aimed at providing an update of the literature published on PD and exposure to pesticides by performing a systematic review and meta-analysis. In addition, we investigated whether methodological differences between studies could explain the heterogeneity in study results.Methods: We identified studies through a systematic literature search. We calculated summary risk ratios (sRRs) for pesticide exposure and subcategories using random effects meta-analyses and investigated sources of heterogeneity by meta-regression and stratified analyses.Results: Thirty-nine case–control studies, four cohort studies, and three cross-sectional studies were identified. An sRR of 1.62 [95% confidence interval (CI): 1.40, 1.88] for pesticide exposure (ever vs. never) was found. Summary estimates for subclasses of pesticides indicated a positive association with herbicides and insecticides, but not with fungicides. Heterogeneity in individual study results was not related to study design, source of control population, adjustment of results for potential confounders, or geographical area. However, results were suggestive for heterogeneity related to differences in the exposure assessment. Job title–based exposure assignment resulted in a higher sRR (2.5; 95% CI: 1.5, 4.1) than did assignment based on self-reported exposure (e.g., for self-reported ever/never exposure, sRR = 1.5; 95% CI: 1.3, 1.8).Conclusions: This review affirms the evidence that exposure to herbicides and insecticides increase the risk of PD. Future studies should focus on more objective and improved methods of pesticide exposure assessment.

Paraoxonase 1 in neurological disorders

“…24,[70][71][72][74][75][76][77][78][79][80][81] Because PON1 is capable of hydrolyzing toxic organophosphates and also has an important antioxidant capacity, the association of PON polymorphisms and PD has been addressed by multiple authors. The frequency of the Met 54 allele of PON1 has been found to be significantly higher in patients with PD compared with control subjects.…”

“…Conversely, there seems to be more solid evidence suggesting that when there is exposure to a toxic environment there is a correlation between the presence of certain genotypes and the development of the disease. 24,70,[73][74][75][76]79,91 PON1, Alzheimer's disease, and other dementias Across the world, the prevalence of dementia is believed to be 24 million, and is expected to double every 20 years until 2040. 26 AD is the foremost cause of dementia starting with compromised memory.…”

Cytoprotective effects of growth factors: BDNF more potent than GDNF in an organotypic culture model of Parkinson's disease

“…However, other studies have failed to find a correlation (84)(85)(86), and the field has thus been widely debated. Recent meta-analyses of numerous epidemiological studies have revealed a significant association between pesticides and PD (7)(8)(9), suggesting that the discrepancy can be attributed to case ascertainment and control selection, study size, diagnostic criteria and assessment of exposure to pesticides.…”

“…Since the discovery of MPTP (73,74), toxins have been intimately linked to PD, and have further gained support from epidemiological studies showing a correlation between environmental toxins and PD (7)(8)(9)(79)(80)(81)(82)(83). To date, however, the mechanism to which these toxins selectively targets dopaminergic cells in the SNpc has been unknown.…”

Risk Factors for Non-communicable Diseases in Vietnam: A Focus on Pesticides

“…In this scenario, the control programs of foods should develop around a food safety framework, based on new production chains, new exposure patterns, and disease scenarios. In fact, developmental exposure to environmental chemical factors may increase the risk of adverse pregnancy outcomes and impact on the programming of neurologic, metabolic, immune and reproductive functions, with major consequences on the risk of a variety of health disorders and NCDs in adult life, from metabolic syndrome, asthma, infertility and other reproductive disorders including puberty disturbances through to diabetes, obesity, cardiovascular and neurodegenerative diseases, and cancer (Costa et al, 2008;Van Der Mark et al, 2012;Mostafalou and Abdollahi, 2013;Tomar et al, 2013;Chevalier and Fénichel, 2014;Fucic and Mantovani, 2014;Jaacks and Staimez, 2015;Khalil et al, 2015). In this frame, according to the International Academy of Ecology and Environmental Sciences (Wenjun et al, 2011), the outbreak of cancer and other serious chronic diseases on a global scale (but especially in economically developing countries) is related to the rising environmental pollution with pesticides, accounting for 5-6%.…”