Air Pollution Tied to Brain Aging

New York Times April 28, 2015

By Nicholas Bakalar

Air pollution is known to increase the risk for stroke and other cerebrovascular disorders. But now researchers have found it is also linked to premature aging of the brain.

The study, in the May issue of Stroke [a medical journal], used data on 943 men and women over 60 who were participants in a larger health study. Researchers did M.R.I. examinations and gathered data on how close the people lived to major highways. They also used satellite data to measure particulate matter smaller than 2.5 micrometers, or PM 2.5, a form of pollution that easily enters the lungs and bloodstream.

After controlling for health, lifestyle and socioeconomic factors, they found that compared with people exposed to the lowest levels of PM 2.5, those with the highest exposure had a 46 percent increased risk for covert brain infarcts, the brain damage commonly called “silent strokes.”

They also found that each additional two micrograms per cubic meter increase in PM2.5 was linked to a decrease in cerebral brain volume equivalent to about one year of natural aging.

“We’re seeing an association between air pollution and potentially harmful attacks on the brain,” said the lead author, Elissa H. Wilker, a researcher at Beth Israel Deaconess Medical Center. “This helps us to better understand the mechanisms related to air pollution and clinically observed outcomes.”

Air pollution + Poverty = Lower IQ

Children born to mothers experiencing economic hardship, who were also exposed during pregnancy to high levels of PAH (polycyclic aromatic hydrocarbons), scored significantly lower on IQ tests at age 5 compared with children born to mothers with greater economic security and less exposure to the pollutants. The findings by researchers at the Columbia University Center for Children’s Environmental Health (CCCEH) at the Mailman School of Public Health appear in the journal Neurotoxicology and Teratology.
PAH are found everywhere in the environment from emissions from motor vehicles, oil, and coal-burning for home heating and power generation, tobacco smoke, and other combustion sources.
The researchers followed 276 mother-child pairs, a subset of CCCEH’s ongoing urban birth cohort study in New York City, from pregnancy through early childhood. Mothers self-reported maternal material hardship during pregnancy and at multiple time points through early childhood. Material hardship is a measure used to assess an individual’s unmet basic needs with regard to food, clothing, and housing. The Columbia researchers, led by Frederica Perera, PhD, DrPH, director of CCCEH, previously reported that that prenatal exposure to airborne PAH during gestation was associated with development delay at age 3, reduced verbal and full scale IQ at age 5, and symptoms of anxiety and depression at age 7.
At child age 7 years, researchers used the Wechsler Intelligence Scale for Children to assess IQ. PAH-DNA adducts in cord blood provided an individual measure of prenatal exposure to the pollutants. The researchers observed that, among children whose mothers reported greater material hardship, the group with high levels of PAH-DNA cord adducts [new chemicals created by the mixture of existing chemicals] significantly scored lower on tests of full scale IQ, perceptual reasoning, and working memory compared to those children with lower levels of adducts. Statistically significant interactions were observed between both prenatal and recurrent material hardship and high levels of cord adducts on children’s working memory scores. The same significant relationships between adducts and IQ were not observed in the low material hardship group.
The findings add to other evidence that socioeconomic disadvantage can increase the adverse effects of toxic physical “stressors” like air pollutants. The present results suggest the need for a multifaceted approach to reduce PAH exposure and alleviate material hardship in order to protect the developing fetus and young child.
“The findings support policy interventions to reduce air pollution exposure in urban areas as well as programs to screen women early in pregnancy to identify those in need of psychological or material support,” says Perera, senior author of the paper.
More on PAH and ways to limit exposure can be found on the CCCEH website.
Story Source:
The above story is based on materials provided by Columbia University’s Mailman School of Public Health. Note: Materials may be edited for content and length.
Journal Reference:

  1. Julia Vishnevetsky, Deliang Tang, Hsin-Wen Chang, Emily L. Roen, Ya Wang, Virginia Rauh, Shuang Wang, Rachel L. Miller, Julie Herbstman, Frederica P. Perera.Combined effects of prenatal polycyclic aromatic hydrocarbons and material hardship on child IQ.Neurotoxicology and Teratology, 2015; DOI: 10.1016/j.ntt.2015.04.002