The role of organochlorine pesticides as environmental factors in Alzheimer's disease in human studies: A systematic review and meta-analysis
Background Alzheimer's disease (AD) is a prevalent neurodegenerative disorder among the elderly, influenced by both genetic and environmental factors. Organochlorine pesticides (OCPs) have recently been identified as potential environmental risk factors due to their bioaccumulation in adipose tissue and neurotoxic properties. Objective This systematic review aimed to examine the human evidence regarding exposure to OCPs and the risk of AD. The results of the meta-analysis showed that exposure to pesticides is significantly associated with an increased risk of AD. Methods A comprehensive search was performed across major scientific databases, including PubMed/MEDLINE, Scopus, Web of Science, the Cochrane Library, and Embase. Results Pooled estimates (random effects meta-analysis) of the four eligible studies showed a significant positive association between exposure to OCPs and the risk of AD (OR = 2.19; 95% CI: 1.40–3.42). These findings indicate that exposure to OCPs may significantly increase the risk of AD. The substantial heterogeneity among studies (I2 = 84.58%) may partly reflect differences in exposure assessment approaches, such as biomonitoring-based measurements compared with occupational or geographically inferred exposure assessments. Conclusions These findings highlight the importance of controlling occupational and environmental exposures to pesticides in preventing neurodegenerative outcomes. The findings suggest that chronic exposure to lipophilic pesticides, particularly persistent chlorinated compounds, may contribute to neurodegenerative processes implicated in the pathophysiology of AD. Therefore, more studies with similar designs and more precise exposure measurements are needed to confirm the results and reduce the heterogeneity.