The Relationship of Organophosphate Pesticide Exposure and Cognitive Decline Among Residents of an Agricultural Area in Northern Thailand.

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 be-tween 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 & PLUSMN; 0.93 units/ml (mean & PLUSMN; SD) and 3.13 & PLUSMN; 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.