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Air pollution linked to brain alteration
A joint study performed by the Barcelona Institute for Global Health (ISGlobal) and the Erasmus University Medical Center of Rotterdam, links residential air pollution during fetal life to brain abnormalities. These abnormalities may contribute to impaired cognitive function seen in school-age children. The study details how air pollution levels now considered safe, are related to alterations of the brain. The work is published in Biological Psychiatry
The study revealed a relationship between exposure to air pollution and difficulty with the inhibition control center in the brain — impulsive behavior related to mental health problems such as addictions and attention-deficit/hyperactivity disorder. A fetus exposed to fine particles may develop a thinner cortex — the outer layer of the brain — in several areas and/or on both brain hemispheres that may explain impairment in that individual's inhibition control later in life.
A population-based cohort study conducted in the Netherlands, enrolled 783 newly pregnant women and then followed their births and those children through school age. Researchers began by assessing the air pollution levels at the women's homes during their pregnancies. This data was collected via air pollution monitoring campaigns of nitrogen dioxide levels, as well as course and fine particulate matter being breathed. Researchers later took brain morphology images of the children when they reached 6 to 10 years old to assess brain development.
The relationship between fine particle exposure, brain structure alteration, and inhibition control was found despite the fact that the average residential levels of fine particles in the study were well below the current European Union (EU) limit.
This finding adds to previous studies that link what government regulations consider to be "acceptable air pollution levels" to other birth complications including cognitive decline and problems in fetal growth. The fetal brain is particularly vulnerable as it hasn't yet developed mechanisms to protect against or remove environmental toxins.
"Although specific individual clinical implications of these findings cannot be quantified, based on other studies, the observed cognitive delays at early ages could have significant long-term consequences such as increased risk of mental health disorders and low academic achievement, in particular due to the ubiquity of the exposure. Therefore, we cannot warrant the safety of the current levels of air pollution in our cities."
Air pollution exposure during fetal life has been related to impaired child neurodevelopment, but it is unclear if brain structural alterations underlie this association. The authors assessed whether air pollution exposure during fetal life alters brain morphology and whether these alterations mediate the association between air pollution exposure during fetal life and cognitive function in school-age children.
We used data from a population-based birth cohort set up in Rotterdam, The Netherlands (2002–2006). Residential levels of air pollution during the entire fetal period were calculated using land-use regression models. Structural neuroimaging and cognitive function were performed at 6 to 10 years of age (n = 783). Models were adjusted for several socioeconomic and lifestyle characteristics.
Mean fine particle levels were 20.2 ?g/m3 (range, 16.8–28.1 ?g/m3). Children exposed to higher particulate matter levels during fetal life had thinner cortex in several brain regions of both hemispheres (e.g., cerebral cortex of the precuneus region in the right hemisphere was 0.045 mm thinner (95% confidence interval, 0.028–0.062) for each 5-?g/m3 increase in fine particles). The reduced cerebral cortex in precuneus and rostral middle frontal regions partially mediated the association between exposure to fine particles and impaired inhibitory control. Air pollution exposure was not associated with global brain volumes.
Exposure to fine particles during fetal life was related to child brain structural alterations of the cerebral cortex, and these alterations partially mediated the association between exposure to fine particles during fetal life and impaired child inhibitory control. Such cognitive impairment at early ages could have significant long-term consequences.
Authors: Mònica Guxens, Ma?gorzata J. Lubczy?ska, Ryan L. Muetzel, Albert Dalmau-Bueno, Vincent W.V. Jaddoe, Gerard Hoek, Aad van der Lugt, Frank C. Verhulst, Tonya White, Bert Brunekreef, Henning Tiemeier, Hanan El Marroun.
The Barcelona Institute for Global Health (ISGlobal) is supported by the "la Caixa" Foundation.
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Different brain regions affected by fine and coarse particles.
Image credit: ISGlobal / Biological psychiatry.