A population-based study conducted in a rural block of West Bengal’s Purba Bardhaman district has revealed worrying levels of cognitive impairment, depression and possible movement disorders among agricultural workers, raising fresh concerns about long-term pesticide exposure and its impact on brain health.
The study, titled, “Pesticide exposure associated with mild cognitive impairment & depression among agricultural workers: Case control study in rural India,” aimed to understand the burden of neurological disorders of neuroinflammatory origin among people aged 50 years and above, designed with robust sampling methods. Researchers expected a minimum 10 per cent prevalence of common neuropsychiatric conditions and calculated a sample size of 138 individuals for initial screening.
Of the 808 individuals screened, 180 (22.3 per cent) tested positive for cognitive impairment, depression, both conditions together or possible movement disorders. Cognitive impairment alone accounted for 56 pc of these cases, while 28.9 pc showed both cognitive impairment and depression. Another 12 participants showed signs of movement disorders.
The demographic profile reflected the agricultural nature of the region with nearly 77 pc of participants being men, and 268 individuals directly involved in farming activities as landowners, sharecroppers or agricultural labourers. Organophosphorus compounds emerged as the most commonly used pesticides, and many workers reported using multiple pesticides simultaneously.
Statistical analysis showed strong associations between neurological symptoms and several agricultural factors. Longer exposure to pesticides over 30 years was significantly linked to higher disease risk. Working more than eight hours a day in the fields and frequent handling of pesticides also showed notable correlations. Men were at higher risk of being screened positive, and lifetime alcohol use had a clear association with neurological symptoms.
Ethnic differences also emerged. Tribal participants recorded lower cognitive scores compared to Bengali participants, falling within ranges suggesting mild cognitive impairment (MCI). Women diagnosed as cases showed significantly lower cognition scores than men, hinting at greater severity despite lower prevalence.
One of the most concerning findings was among agricultural labourers who worked exclusively in farming. This subgroup recorded the lowest cognitive scores, highest impairment in daily living and the highest depression scores. These observations underlined the elevated vulnerability of workers directly exposed to pesticides compared to landowners or sharecroppers who may also have other occupations.
The study also measured biomarkers such as AChE, BChE and PON1 that typically indicate organophosphorus exposure. While no significant case-control differences were found, researchers believe this was due to underpowered sampling caused by pandemic-related disruptions. Still, PON1 levels were noticeably higher in participants working longer daily hours or using pesticides more frequently, suggesting sensitivity to exposure intensity. When placed against national and global research, the study’s findings align with broader evidence. Previous studies have linked pesticide exposure to cognitive decline in countries such as Korea, Greece, Mexico and Chile. International research also shows that depression often co-exists with cognitive impairment, sometimes reaching up to 32 pc prevalence, mirroring this study’s observation of 33 pc. Movement disorder indications, though low at 1.5 pc, are consistent with global Parkinson’s disease prevalence in seniors.
However, the researchers acknowledged certain limitations. “Because all participants lived in the same agricultural zone, even controls may have had indirect exposure to pesticides, potentially affecting comparisons. A third control group from a non-agricultural area would strengthen future research,” they said. The team also noted that the original plan to provide clinical diagnoses by neurologists could not proceed due to COVID-19 restrictions.
Despite these limitations, the study presents a clear and concerning picture. Prolonged and intensive exposure to pesticides is emerging as a major risk factor for neurological problems in rural farming communities. With neuroinflammatory diseases increasing worldwide, the findings underline the need for safer pesticide practices, greater awareness among farmers, and long-term monitoring to understand how continuous exposure may contribute to cognitive and neurological decline.
