Environmental Pyrethroid Exposure and Cognitive Dysfunction in U.S. Older Adults: The NHANES 2001–2002

Pyrethroid compounds are widely used in household insecticides and agricultural pesticides. Recent studies, however, report that pyrethroid exposures affect neurobehavioral function in animals and may be associated with adverse neurocognitive development in children. This study aimed to examine the association between pyrethroid exposure and cognitive dysfunction in older adults using a well-defined general population. We analyzed data from 336 individuals, aged 60–84 years, who participated in the National Health and Nutrition Examination Survey 2001–2002. We used urinary 3-phenoxybenzoic acid (3-PBA) concentration as a biomarker of pyrethroid exposures and assessed cognitive function with the digit–symbol coding test. The geometric means (±geometric standard errors) of creatinine-uncorrected and corrected urinary 3-PBA were 0.30 (±0.87) μg/L and 0.36 (±0.89) μg/g. After adjusting for sociodemographic factors, higher 3-PBA concentrations (> vs. ≤0.30 μg/g creatinine (median)) were associated with lower scores of cognitive function (−3.83 95% confidence interval: −7.11, −0.54). Significance was persistent after additionally adjusting for physical activity and smoking pack-year (−3.76 95% CI: −7.16, −0.36) and further adjusting for BMI and presence of hypertension and diabetes (−3.82 95% CI: −6.92, −0.71). Our findings suggest that pyrethroid exposure is associated with cognitive dysfunction in older adults.

Dissociable Multi-scale Patterns of Development in Personalized Brain Networks

The brain is organized into networks at multiple resolutions, or scales, yet studies of functional network development typically focus on a single scale. Here, we derived personalized functional networks across 29 scales in a large sample of youths (n=693, ages 8-23 years) to identify multi-scale patterns of network re-organization related to neurocognitive development. We found that developmental shifts in inter-network coupling systematically adhered to and strengthened a functional hierarchy of cortical organization. Furthermore, we observed that scale-dependent effects were present in lower-order, unimodal networks, but not higher-order, transmodal networks. Finally, we found that network maturation had clear behavioral relevance: the development of coupling in unimodal and transmodal networks dissociably mediated the emergence of executive function. These results delineate maturation of multi-scale brain networks, which varies according to a functional hierarchy and impacts cognitive development.