Alzheimer's-like brain changes seen in young who breathed polluted air.

Jan 30, 2012

Calderon-Garciduenas, L, M Kavanaugh, M Block, AD Angiulli, R Delgado-Chavez, R Torres-Jardon, A Gonzalez-Maciel, R Reynoso-Robles, N Osnaya, R Villarreal-Calderon, R Guo, H Zhaowei, Z Hongtu, G Perry and P Diaz. 2011. Neuroinflammation, Alzheimer's disease-associated pathology, and down-regulation of the prion-related protein in air pollution-exposed children and young adults. Journal of Alzheimer's Disease http://dx.doi.org/10.3233/JAD-2011-110722.

Synopsis by Heather Volk

A study examining postmortem brains of children and young adults suggests that exposure to air pollution causes changes in the brain that are similar to those seen in Alzheimer's patients.

Children and young adults from areas with highly polluted air in Mexico had physical and genetic changes in their brains akin to those found in adults with Alzheimer's disease.

The changes seen are surprising because they are not supposed to occur in younger brains. Alzheimer's afflicts older adults and those in middle age with specific family genetics. Experts are not sure what causes the onset in older age but think environment might play a role.

This study builds on a growing body of research suggesting that air pollution exposure can affect the brain. Previous studies have found links between air pollution exposure and signs of inflammation – a basic body response that indicates injury – in dog and mice brains.

The team of researchers from North America examined 43 brains from children and young adults who died in accidents. More than half were younger than 17 years old and the oldest was 40. Thirty-five cases came from urban, highly polluted Mexico City, while the eight controls were from the rural, unpolluted areas of Tlaxcala and Veracruz. They looked for changes in gene expression, immune markers and physical indicators similar to those associated with Alzheimer's disease. Results from pollution-exposed city dwellers were compared with those from the rural areas.

The gene expression analysis showed there were differences between locations in how the genes work. More than 100 genes were changed in the brains from subjects who lived in urban areas when compared to brains from those who lived in the country.

Over half of the brains from the urban areas showed signs of amyloid-B plaques and 40 percent had pretangle material. In contrast, none of the brains from the rural areas had either condition. Amyloid-B plaques are protein deposits commonly found in the brains of person with Alzheimer's. Pretangle material is often a precursor and is also associated with the disease.

Since the APO-E gene is linked with early-onset Alzheimer's disease, the authors also examined whether the risk version of this gene was linked with similar Alzheimer's pathology. They found that persons with the APO-E risk genotype were more likely to have the plaques commonly linked with Alzheimer's in the brain.

While air pollution was not directly measured, monitoring data show Mexico City's air quality consistently ranks as some of the worst in the world. Residents, such as those in the study, would be exposed to traffic and industrial pollution throughout their lives.

Many questions remain unanswered, say the authors, who suggest long-term and comprehensive studies "into the association between air pollution exposures and CNS damage in children is of pressing importance for public health."

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