Supplementary Material for: Effects of ambient air pollution on brain cortical thickness and subcortical volume: A longitudinal neuroimaging study

Introduction: Long-term exposure to air pollutants is associated with an increased risk of Alzheimer’s disease and mild cognitive impairment. Therefore, we investigated the association between long-term air pollution exposure and changes in neuroimaging markers.
Methods: In this longitudinal study, we studied a prospective cohort of 361 adults residing in four cities in the Republic of Korea. Long-term concentrations of particulate matter with aerodynamic diameters of ≤10 μm (PM10) and ≤2.5 μm (PM2.5) and nitrogen dioxide (NO2) at residential addresses were estimated. Neuroimaging markers (cortical thickness and subcortical volume) were obtained from brain magnetic resonance images at baseline (August 2014 to March 2017) and at the 3-year follow-up (until September 2020). Linear mixed-effects models were used, adjusting for covariates.
Results: A 10-μg/m3 increase in PM10 was associated with reduced whole-brain mean (β= -0.45, standard error (SE)= 0.10, P< 0.001), frontal (β= -0.53, SE= 0.11; P< 0.001) and temporal thicknesses (β= -0.37, SE= 0.12; P= 0.002). A 10-ppb increase in NO2 was associated with a decline in the whole brain mean cortical thickness (β= -0.23, SE= 0.05; P< 0.001), frontal (β= -0.25, SE= 0.05; P< 0.001), parietal (β= -0.12, SE= 0.05; P= 0.025), and temporal thicknesses (β= -0.19, SE= 0.06; P= 0.001). Subcortical structures associated with air pollutants include the thalamus volume.
Conclusions: Long-term exposure to PM10 and NO2 may lead to cortical thinning in adults.

引言：长期暴露于空气污染物与阿尔茨海默病（Alzheimer’s Disease）及轻度认知障碍（mild cognitive impairment）的发病风险升高相关。为此，本研究探讨了长期暴露于空气污染物与神经影像标志物变化之间的关联。
方法：本项纵向研究纳入了361名居住于韩国四座城市的成年人组成的前瞻性队列。研究估算了研究对象住宅地址处的长期空气污染物浓度，包括空气动力学直径≤10微米的颗粒物（PM10）、≤2.5微米的颗粒物（PM2.5）以及二氧化氮（NO2）。分别于基线阶段（2014年8月至2017年3月）及3年随访阶段（截至2020年9月）通过脑部磁共振成像获取神经影像标志物，即皮层厚度与皮层下体积。本研究采用线性混合效应模型进行分析，并对协变量进行了校正。
结果：PM10每升高10微克/立方米，与全脑平均皮层厚度（β=-0.45，标准误（SE）=0.10，P<0.001）、额叶皮层厚度（β=-0.53，SE=0.11；P<0.001）及颞叶皮层厚度（β=-0.37，SE=0.12；P=0.002）的降低显著相关。二氧化氮每升高10ppb，与全脑平均皮层厚度（β=-0.23，SE=0.05；P<0.001）、额叶皮层厚度（β=-0.25，SE=0.05；P<0.001）、顶叶皮层厚度（β=-0.12，SE=0.05；P=0.025）及颞叶皮层厚度（β=-0.19，SE=0.06；P=0.001）的下降显著相关。与空气污染物相关的皮层下结构包括丘脑体积。
结论：成年人长期暴露于PM10与NO2可能导致皮层变薄。