Story at a glance
- Air pollution affects health in many ways, including increased risk of premature births.
- Researchers are interested in investigating potential effects of chronic traffic pollution on brain health and Alzheimer’s disease.
- An experiment with mice that were housed near a traffic tunnel suggests that exposure to air pollution may accelerate the development of Alzheimer’s symptoms.
Researchers are concerned that we don’t yet know the full range of health effects of air pollution, especially traffic-related air pollution. Early studies drew links between higher concentrations of pollution to increased probability for premature births and low birth weights, but experts now are also studying how chronic exposure over time can affect aging and the brain.
To examine that potential link, researchers put mice near a traffic tunnel to mimic long-term exposure to air pollution from cars. The study published in Environmental Health Perspectives goes into detail on how the researchers set up the experiments. The team was specifically interested in how the traffic pollution would affect mice with a gene that predisposes them to Alzheimer’s disease. Mice with and without the gene were housed near a tunnel in Northern California for up to 14 months.
The researchers wanted to see what happened to these mice after living so close to the tunnel. “This approach was a creative way to get at the question of what impacts air pollution has on the brain in the absence of confounding factors such as socioeconomic influences, diet, etc.,” toxicologist Pamela Lein at the University of California, Davis says in a press release. “It's important to know if living close to these roadways poses a significant risk to the human brain as it ages.”
Lein and collaborators tested mice of different ages to see what the effects would be on various brain ages in the animals. They found that the exposure to pollution accelerated characteristics of Alzheimer’s in both groups of mice that had the related risk gene and the ones without.
“The big, exciting discovery is that traffic-related air pollution is a risk factor for late-onset Alzheimer's disease. We didn't anticipate that,” says Lein. “This is important because this pollution is everywhere and could explain the increased number of people impacted by Alzheimer's disease across the world.”
The researchers are not yet sure why this might be happening. It may have to do with the types of gases in pollution, the particulate matter or other factors like dust, vibration and noise. The size of the particulate matter may also be important.
“The next set of studies is to try and tease apart specific components of traffic-related air pollution that drive these Alzheimer's disease traits,” says Lein in the press release. “Or is it the collective mix that causes the damage?”
These studies could have important implications for national policy that regulates air pollution. “If we could make some progress in identifying which component in traffic-related air pollution is causing these effects, then scientists can approach legislators to develop scientifically based regulations,” says Lein. “Even if we can delay onset of Alzheimer's disease by five years, we could potentially save our health care system an enormous amount of money.”
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