Department of Preventive Medicine, Keck School of Medicine of University of Southern California, Los Angeles, CA 90063, USA.
Department of Preventive Medicine, Keck School of Medicine of University of Southern California, Los Angeles, CA 90063, USA; Department of Neurology, Keck School of Medicine of University of Southern California, Los Angeles, CA 90063, USA.
Environ Int. 2020 Oct;143:105933. doi: 10.1016/j.envint.2020.105933. Epub 2020 Jul 10.
Emerging findings have increased concern that exposure to fine particulate matter air pollution (aerodynamic diameter ≤ 2.5 μm; PM) may be neurotoxic, even at lower levels of exposure. Yet, additional studies are needed to determine if exposure to current PM levels may be linked to hemispheric and regional patterns of brain development in children across the United States.
We examined the cross-sectional associations between geocoded measures of concurrent annual average outdoor PM exposure, regional- and hemisphere-specific differences in brain morphometry and cognition in 10,343 9- and 10- year-old children.
High-resolution structural T1-weighted brain magnetic resonance imaging (MRI) and NIH Toolbox measures of cognition were collected from children at ages 9-10 years. FreeSurfer was used to quantify cortical surface area, cortical thickness, as well as subcortical and cerebellum volumes in each hemisphere. PM concentrations were estimated using an ensemble-based model approach and assigned to each child's primary residential address collected at the study visit. We used mixed-effects models to examine regional- and hemispheric- effects of PM exposure on brain estimates and cognition after considering nesting of participants by familial relationships and study site, adjustment for socio-demographic factors and multiple comparisons.
Annual residential PM exposure (7.63 ± 1.57 µg/m) was associated with hemispheric specific differences in gray matter across cortical regions of the frontal, parietal, temporal and occipital lobes as well as subcortical and cerebellum brain regions. There were hemispheric-specific associations between PM exposures and cortical surface area in 9/31 regions; cortical thickness in 22/27 regions; and volumes of the thalamus, pallidum, and nucleus accumbens. We found neither significant associations between PM and task performance on individual measures of neurocognition nor evidence that sex moderated the observed associations.
Even at relatively low-levels, current PM exposure across the U.S. may be an important environmental factor influencing patterns of structural brain development in childhood. Prospective follow-up of this cohort will help determine how current levels of PM exposure may affect brain development and subsequent risk for cognitive and emotional problems across adolescence.
新出现的研究结果表明，即使在较低的暴露水平下，细颗粒物空气污染（空气动力学直径≤2.5μm；PM）也可能具有神经毒性。然而，还需要更多的研究来确定目前的 PM 水平暴露是否与美国儿童半球和区域大脑发育模式有关。
我们研究了在 10343 名 9 至 10 岁儿童中，经地理编码的当前年度平均户外 PM 暴露水平与大脑形态和认知的区域和半球特异性差异之间的横断面关联。
从 9 至 10 岁的儿童中采集高分辨率结构 T1 加权脑磁共振成像（MRI）和 NIH 工具包认知测量数据。使用 FreeSurfer 来量化每个半球的皮质表面积、皮质厚度以及皮质下和小脑体积。使用基于集合的模型方法估计 PM 浓度，并将其分配给每个儿童在研究访问时收集的主要居住地址。我们使用混合效应模型，在考虑参与者按家族关系和研究地点嵌套、调整社会人口因素和多次比较后，研究 PM 暴露对大脑估计和认知的区域和半球效应。
每年的住宅 PM 暴露（7.63±1.57µg/m）与额叶、顶叶、颞叶和枕叶以及皮质下和小脑脑区的灰质半球特异性差异有关。PM 暴露与 9/31 个皮质区域的皮质表面积之间存在半球特异性关联；与 22/27 个区域的皮质厚度之间存在半球特异性关联；与丘脑、苍白球和伏隔核的体积之间也存在半球特异性关联。我们既没有发现 PM 与个别神经认知测量任务表现之间存在显著关联，也没有证据表明性别调节了观察到的关联。
即使在相对较低的水平，美国目前的 PM 暴露量也可能是一个重要的环境因素，影响儿童时期的大脑结构发育模式。对该队列的前瞻性随访将有助于确定目前的 PM 暴露水平如何影响大脑发育以及随后在青春期出现认知和情绪问题的风险。
