Childhood exposure to organophosphate pesticides: Functional connectivity and working memory in adolescents

Background: Early life exposure to organophosphate (OP) pesticides is linked with adverse neurodevelopment and brain function in children. However, we have limited knowledge of how these exposures affect functional connectivity, a measure of interaction between brain regions. To address this gap, we examined the association between early life OP pesticide exposure and functional connectivity in adolescents. Methods: We administered functional near-infrared spectroscopy (fNIRS) to 291 young adults with measured prenatal or childhood dialkylphosphates (DAPs) in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study, a longitudinal study of women recruited during pregnancy and their offspring. We measured DAPs in urinary samples collected from mothers during pregnancy (13 and 26 weeks) and children in early life (ages 6 months, 1, 2, 3, and 5 years). Youth underwent fNIRS while they performed executive function and semantic language tasks during their 18-year-old visit. We used covariate-adjusted regression models to estimate the associations of prenatal and childhood DAPs with functional connectivity between the frontal, temporal, and parietal regions, and a mediation model to examine the role of functional connectivity in the relationship between DAPs and task performance. Results: We observed null associations of prenatal and childhood DAP concentrations and functional connectivity for the entire sample. However, when we looked for sex differences, we observed an association between childhood DAPs and functional connectivity for the right interior frontal and premotor cortex after correcting for the false discovery rate, among males, but not females. In addition, functional connectivity appeared to mediate an inverse association between DAPs and working memory accuracy among males. Conclusion: In CHAMACOS, a secondary analysis showed that adolescent males with elevated childhood OP pesticide exposure may have altered brain regional connectivity. This altered neurofunctional pattern in males may partially mediate working memory impairment associated with childhood DAP exposure.