Background: Organophosphate pesticide (OP) exposure may be associated with the subsequent development of cognitive decline, which is used to assess the early stage of Alzheimer’s disease. We investigated the correlations between biomarkers of OP exposure and cognitive decline among farmers and nonfarmers.
Methods: Blood samples were collected from 98 participants. Biomarkers of OP exposure were analyzed, including acetylcholinesterase enzyme (AChE) and butyrylcholinesterase enzyme (BChE) activity. Cognitive decline was measured using the Thai Mental State Examination.
Results: The average AChE and BChE activity levels were 3.94±0.93 units/ml (mean ±SD) and 3.13±0.88 units/ml, respectively. Being employed in agricultural occupations were positively correlated with cognitive decline, even after adjustment for sex, age, and educational level (odds ratio: 5.469, 95% CI 1.012-29.55). There was significantly lower AChE activity in participants who had used pesticides for more than 10 years. There was also a positive correlation between low AChE activity and cognitive decline in the study population.
Conclusion: The monitoring of exposure biomarkers may be useful in investigating the risk of cognitive decline in at-risk groups.
Wongta A, Hongsibsong S, Xu Z,
The Relationship of Organophosphate Pesticide Exposure and Cognitive Decline Among Residents of an Agricultural Area in Northern Thailand..
J Health Res.
 Pretty J, Bharucha ZP. Integrated pest management for sustainable intensification of agriculture in Asia and Africa. Insects2015;6(1):152-82. https://doi.org/10.3390/ insects6010152.
 Agency for Toxic Substances and Disease Registry [ATSDR]. Public health statement for chlorpyrifos [cited 2021 15 Aug]. Available from: https://wwwn.cdc.gov/TSP/PHS/PHS.aspx? phsid¼493&toxid¼88.
 U.S. Environmental Protection Agency. Revised human health risk assessment on chlorpyrifos [cited 2021Aug15]. Available from: https://www.epa.gov/ingredients-used pesticide-products/revised-human-health-risk-assessmentchlorpyrifos.
 Shelton JF, Hertz-Picciotto I, Pessah IN. Tipping the balance of autism risk: potential mechanisms linking pesticides and autism. Environ Health Perspect 2012;120(7):944-51.https:// doi.org/10.1289/ehp.1104553.
 Pesticide-induced diseases database [cite 2021 Aug18]. Available from: https://www.beyondpesticides.org/ resources/pesticide-induced-diseases-database/overview.
 Hayden KM, Norton MC, Darcey D, Ostbye T, Zandi PP, Breitner JC, et al. Occupational exposure to pesticides increases the risk of incident AD: the Cache County study. Neurology 2010;74(19):1524-30. https://doi.org/10.1212/ WNL.0b013e3181dd4423.
 Thany SH, Reynier P, Lenaers G. Neuro toxicity of pesticides: its relationship with neuro degenerative diseases. Med Sci (Paris)2013;29(3):273-8. https://doi.org/10.1051/medsci/ 2013293013.
 2020 Alzheimer's disease facts and figures. Alzheimers Dement 2020.https://doi.org/10.1002/alz.12068 (in press).
 Ernst RL, Hay JW. The US economic and social costs of Alzheimer's disease revisited. Am J Publ Health 1994;84(8): 1261-4.https://doi.org/10.2105/ajph.84.8.1261.
 Yadav SS, Singh MK, Yadav RS. Organophosphates induced alzheimer's disease: an epigenetic aspect. J Clin Epigenet 2016;2(1):1-8.https://doi.org/10.21767/2472-1158.100010.
 Carter J, Lippa CF. Beta-amyloid, neuronal death and Alzheimer's disease. Curr Mol Med 2001;1(6):733-7.https:// doi.org/10.2174/1566524013363177.
 Yan D, Zhang Y, Liu L, Yan H. Pesticide exposure and risk of Alzheimer's disease: a systematic review and meta-analysis. Sci Rep 2016;6:32222.https://doi.org/10.1038/srep32222.
 Campdelacreu J. Parkinson disease and Alzheimer disease: environmental risk factors. Neurologia 2014;29(9):541-9. https://doi.org/10.1016/j.nrl.2012.04.001.
 World Health Organization [WHO]. WHO mortality database [cite 2022 October 31]. Available from: https://platform. who.int/mortality/themes/theme-details/topics/indicatorgroups/indicator-group-details/MDB/alzheimer-and-otherdementias.
 Ministry of Labour. Office of Permanent Secretary. Labour statistical year book 2021[cite 2022 October 19]. Available from: https://www.mol.go.th/wp-content/uploads/sites/2/ 2022/08/FinalreportStatictis2564-for16Aug2565.pdf.
 Lionetto MG, Caricato R, Calisi A, Giordano ME, Schettino T. Acetylcholinesterase as a biomarker in environmental and occupational medicine: new insights and future perspectives. Bio Med Res Int 2013;2013:321213. https://doi.org/10.1155/2013/321213.
 Trainthe Brain Forum Committee. Thai mental state examination (TMSE). Siriraj Hosp Gaz1993;45:359-74.
 Ministry of Public Health, Department of Medical Services, Institute of Geriatric Medicine. Study of the correlation of the mini-mental state examination Thai version (MMSE-Thai) 2002 and Thai mental state examination (TMSE) to screen dementia in elderly people [cited 2021 Dec15]. Available from: http://agingthai.dms.go.th/agingthai/wp-content/ uploads/2020/07/book_14.pdf.
 Ellman GL, Courtney KD, Andres Jr V. Feather-Stone RM. A new and rapid colorimetric determination of acetylcholinesterase activity. Biochem Pharmacol 1961;7:88-95.https:// doi.org/10.1016/0006-2952(61)90145-9.
 Jintana S, Sming K, Krongtong Y, Thanyachai S. Cholinesterase activity, pesticide exposure and health impact in a population exposed to organophosphates. Int Arch Occup Environ Health 2009;82(7):833-42. https://doi.org/10.1007/ s00420-009-0422-9.
 Brock A. Cholinesterase in healthy adults. Significance of sex, age, weight and height for activation of P-cholinesterase. Ugeskr Laeger 1990;152(17):1233-5.
 deFrias CM, Nilsson LG, Herlitz A. Sex differences in cognition are stable overa10-year period in adulthood and old age. Neuropsychol Dev Cogn B Aging Neuropsychol Cogn 2006;13(3e4):574e87. https://doi.org/10.1080/ 13825580600678418.
 Proust-Lima C, Amieva H, Letenneur L, Orgogozo JM, Jacqmin-Gadda H, Dartigues JF. Gender and education impact on brain aging: a general cognitive fact or approach. Psychol Aging 2008;23(3):608-20. https://doi.org/10.1037/ a0012838.
 Fotenos AF, Mintun MA, Snyder AZ, Morris JC, Buckner RL. Brain volume decline in aging: evidence for a relation between socio economic status, preclinical Alzheimer disease, and reserve. Arch Neurol 2008;65(1):113-20.https://doi.org/ 10.1001/archneurol.2007.27.
 Ferreira L, Ferreira Santos-Galduroz R, Ferri CP, Fernandes Galduroz JC. Rate of cognitive decline in relation to sex after 60 years-of-age: a systematic review. Geriatr Gerontol Int 2014;14(1):23-31.https://doi.org/10.1111/ggi.12093.
 Lovden M, Fratiglioni L, Glymour MM, Lindenberger U, Tucker-Drob EM. Education and cognitive functioning across the lifespan. Psychol Sci Publ Interest 2020;21(1):6-41. https://doi.org/10.1177/1529100620920576.
 Clouston SAP, Smith DM, Mukherjee S, Zhang Y, Hou W, Link BG, et al. Education and cognitive decline: an integrative analysis of global longitudinal studies of cognitive aging. J Gerontol B Psychol Sci Soc Sci 2020;75(7):151-60.https:// doi.org/10.1093/geronb/gbz053.
 Kim JY, Park SJ, Kim SK, Kim CS, Kim TH, Min SH, et al. Pesticide exposure and cognitive decline in a rural South Korean population. PLoS One 2019;14(3):0213738.https:// doi.org/10.1371/journal.pone.0213738.
 Steenland K, Wesseling C, Roman N, Quiros I, Juncos JL. Occupational pesticide exposure and screening tests for neuro degenerative disease among an elderly population in Costa Rica. Environ Res 2013;120:96-101.https://doi.org/ 10.1016/j.envres.2012.08.014.
 Malueka RG, Rahman A, Dwianignsih EK, Panggabean AS, Bayuangga HF, Alifaningdyah S, et al. Blood cholinesterase level is associated with cognitive function in Indonesian school-age children exposed to pesticides. Open Access Maced J Med Sci 2020;8(E):81-6. https://doi.org/10.3889/ oamjms.2020.3985.
 Ramírez-Santana M, Zúniga L, Corral S, Sandoval R, Scheepers PTJ, Vander Velden K, et al. Assessing biomarker sand neuropsychological outcomes in rural populations exposed to organophosphate pesticides in Chilee study design and protocol. BMC Publ Health 2015;15(1):116. https://doi.org/10.1186/s12889-015-1463-5.