A growing body of evidence is indicating that air pollution can have a detrimental impact on cognitive functions, and behavioral development in children. Now, researchers believe they have found a gene that underlies that connection; they found that one variation of the APOE gene, called the ε4 variant, is a critical player. The work, by scientists at the Barcelona Institute for Global Health (ISGlobal), has been reported in Environmental Health Perspectives.
This study follows up on earlier work, the BREATHE project, which found that air pollution was associated with decreased cognitive development, more behavioral problems, and changes in brain structure in the kids that participated.
This study assessed data from more than 1,600 children in Barcelona. While people all carry the same genes, there are many small differences within those genes, called gene variants; the research team looked at a variant of the APOE gene called ε4. They found that kids with that variant experienced a more significant adverse effect on their neurodevelopment from pollution related to traffic. Carriers with the ε4 variant developed attention span more slowly and had more behavior problems. A region of their brains called the caudate nucleus also tended to be smaller.
"These findings suggest that children who carry this [variant] could be more vulnerable to the detrimental effects that air pollution has on important aspects of their neurodevelopment," explained the lead author of the study, Silvia Alemany, ISGlobal researcher.
"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," Alemany added.
While genetic data was readily available for the study participants, their cognitive and behavioral functions were tested, including an assessment for symptoms of attention deficit hyperactivity disorder. For 163 participants, magnetic resonance imaging data were also available.
"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," noted Jordi Sunyer, ISGlobal researcher and director of the BREATHE project. "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 video above, from UNICEF, has more about protecting kids from air pollution.