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A recent study conducted by the Barcelona Institute for Global Health (ISGlobal), backed by the “la Caixa” Foundation, has uncovered significant findings regarding the detrimental effects of air pollution on children’s brain development. Published in Environment International, the study emphasizes the risks posed by early exposure to polluted air, revealing that children who encounter higher pollution levels during their formative years show weaker connections among critical brain regions.
The research indicated a decrease in functional connectivity both within and between various cortical and subcortical brain networks. These networks comprise groups of interconnected brain structures that collectively facilitate various cognitive processes, including perception, motor control, and reasoning. Previous studies have suggested a link between air pollution and altered functional connectivity in the brain, particularly in developing children. Nonetheless, the specific mechanisms by which air pollution influences the development and maturation of these brain networks remain largely unclear.
In this study, researchers analyzed data from 3,626 children participating in the Generation R cohort in Rotterdam, Netherlands. They estimated the levels of air pollution—specifically particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), and nitrogen oxides (NOX)—based on the environmental conditions surrounding the children’s residences. The assessment of brain connectivity involved examining connections both within and across 13 cortical networks and three subcortical regions: the amygdala, responsible for emotional processing; the hippocampus, essential for memory and spatial awareness; and the caudate nucleus, involved in movement and decision-making.
The children underwent resting-state neuroimaging scans at two distinct time intervals, first around the age of 10 and again at approximately 14 years old. The researchers analyzed pollution exposure during two crucial periods: from birth to three years old and in the year preceding the brain assessments.
“This study stands out as one of the first to delve into how air pollution influences brain connectivity at rest, leveraging brain scans collected over time from a large cohort of children,” noted Michelle Kusters, ISGlobal researcher and the lead author of the study.
Long-term Effects During Adolescence
The findings indicated that children exposed to greater levels of air pollution from birth to three years old exhibited diminished connectivity between the amygdala and cortical networks involved in attention, somatomotor functions (which govern body movements), and auditory processing. Additionally, increased exposure to PM10 particles in the year prior to the neuroimaging showed a link to lower functional connectivity between the salience and medial-parietal networks, which are crucial for environmental stimulus detection and self-reflection.
“The persistence of these associations into adolescence suggests that early pollution exposure may cause enduring disruptions in the typical development of brain networks, potentially impacting emotional processing and cognitive abilities,” explained Mònica Guxens, an ICREA researcher at ISGlobal and co-author of the study. “Further investigations are essential to fully understand these findings and their implications for brain development,” she stressed.
Impact on Brain Volume
Moreover, a related study from the same research team explored how air pollution exposure during pregnancy and childhood correlates with changes in brain volume through adolescence. This analysis included data from 4,243 children within the Generation R cohort, who were assessed multiple times for various brain structures, including white matter, cortical grey matter, the cerebellum, and seven subcortical volumes.
Results indicated that exposure to fine particles (PM2.5) and copper during pregnancy was linked to reduced hippocampal volume at age 8, a critical area for memory function. However, the team observed signs of “compensatory growth” in the hippocampus as the children aged, suggesting that the brain might adapt to some extent, mitigating the initial adverse effects of pollution exposure. Despite the observable changes in hippocampal volume, no significant alterations were reported in other brain structures, including white matter, cortical grey matter, or the cerebellum.
The Necessity for Policy Intervention
The findings of these studies strongly highlight the potential long-term implications of early exposure to air pollution on brain connectivity and overall development. “While certain brain regions may be capable of compensatory growth, the ongoing disruptions in functional networks call for more exploration into the underlying mechanisms at play. Given the widespread nature of air pollution, these results reiterate the urgent need for effective policies aimed at reducing pollution, especially in urban areas, to protect children’s brain health,” emphasized Michelle Kusters.
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