Previous research has shown that exposure to air pollution is linked to diminished cognitive development, increased behavioral problems, and even structural differences in the brains of children. And yet the mechanisms behind these associations have remained a mystery.
In a new study, researchers at the Barcelona Institute for Global Health (ISGlobal) in Spain have discovered that a certain gene variant often implicated in Alzheimer’s disease may play a significant role in this process.
The scientists analyzed data from over 1,600 children attending 39 schools in Barcelona and observed that the association between exposure to traffic-related pollution and adverse effects on neurodevelopment was more significant in the children who carried the ε4 allele of the APOE gene.
Carriers of this genetic variant had higher behavior problem scores and their attention capacity developed more slowly. Moreover, the volume of the caudate nucleus — an anatomical brain structure — tended to be smaller in that group.
“These findings suggest that children who carry this allele could be more vulnerable to the detrimental effects that air pollution has on important aspects of their neurodevelopment,” explained Silvia Alemany, ISGlobal researcher and lead author of the study.
“Systemic inflammation and oxidative stress are two of the most well-established mechanisms underlying the adverse health effects of air pollution. Interestingly, both these mechanisms are also involved in the pathogenesis of dementia. In fact, research has demonstrated an association between exposure to air pollution and cognitive impairment in older people.”
“All these considerations, and the fact that APOE ε4 is the most important known genetic risk factor for Alzheimer’s disease, led us to wonder whether the allele might also have a relationship with the adverse effects air pollution has on brain function in children.”
Genetic data were available for all of the children. Tests were also conducted to assess cognitive function, behavioral problems and possible symptoms of attention-deficit/hyperactivity disorder (ADHD). Traffic-related air pollution levels were calculated on the basis of actual measurements. Magnetic resonance imaging (MRI) data were available for 163 of the study participants.
“More research will be needed in other populations to replicate these results and we need to establish whether this possible genetic vulnerability also applies to exposure to air pollution during earlier stages of development, for example, in the prenatal period,” warns ISGlobal researcher Jordi Sunyer, who is also director of the BREATHE project, an agency that collects and distributes scientific information on air quality in Pittsburgh, southwestern Pennsylvania and beyond.
“In any case, once again the findings are clear: it is essential to implement measures to reduce traffic in the urban environment and, particularly, in places where children are present, such as the areas around schools.”
The findings are published in the journal Environmental Health Perspectives.