A new study by Emory University researchers has found a link between traffic-related air pollution and Alzheimer's disease in humans.
Researchers used brain tissue donated by residents of the Atlanta metropolitan area to assess their home addresses for air pollution caused by nearby traffic. A study published Wednesday does not prove that air pollution causes Alzheimer's disease, but it does show a link between exposure to air pollution from traffic and signs of Alzheimer's disease in brain tissue. found.
Medical and environmental authorities have long warned about the effects of air pollution on respiratory and heart health.
The study contributes to existing evidence that respiratory pollution can cause “plaques” or deposits in the brain that are a hallmark of Alzheimer's disease.
“This is concerning because much of the reason Atlanta's air pollution is so high is because of traffic,” said Anke Huels, lead author of the study and assistant professor of epidemiology at Emory's Rollins School of Public Health. “That's also why we focused specifically on traffic-related air pollution.”
This study is one of the first to examine the link between air pollution and signs of Alzheimer's disease in human brain samples, she said. The research results were published in the American Academy of Neurology's medical journal Neurology.
The brain tissue used in the study was taken from 224 donors who died before 2020 and are housed in the brain bank at Emory's Goizeuta Alzheimer's Disease Research Center. Patients lived in urban or suburban areas in a 20-county metropolitan area. Most patients were white, 59% were male, and the average age at death was 76 years.
Most of the brains studied were from people who had already been diagnosed with Alzheimer's disease or other dementias before they died.
Although the study population is not comparable to the general population, the findings are still valuable because they show that pollution is associated with plaques in the brain, Huels said.
More than 6.7 million U.S. residents have been diagnosed with Alzheimer's disease, including at least 150,000 Georgians.
Alzheimer's disease, a type of dementia, is a progressive disease that affects memory and other brain functions, according to the Alzheimer's Association. Researchers do not know the exact cause of Alzheimer's disease, but it is likely due to a variety of genetic and environmental factors. Air pollution has long been suspected as a potential contributing factor.
“Our study used an air pollution model that allows us to obtain estimates of residential traffic-related air pollution concentrations at very fine resolution up to 200 to 250 meters,” Huels said. I am. “Of course, these pollutants are found at the highest levels around major highways, so people who live in close proximity to major highways have the highest exposure to traffic-related pollutants. is.”
The study looked at whether there was a link between 'fine particulate matter' from traffic exhaust, breathing polluted air and signs of Alzheimer's disease in the brain. According to the Environmental Protection Agency, particulate pollution is made up of tiny solid or liquid particles that are so small that they can be inhaled deep into the lungs and enter the bloodstream, causing health problems.causing haze to form in some areas of the United States
Huels said the findings are consistent with previous studies that have shown a link between particle pollution and cognitive decline, memory loss or Alzheimer's disease diagnosis.
The researchers also looked at patients who carried the APOE gene, a major genetic risk factor for developing Alzheimer's disease. However, the strongest association between pollution and Alzheimer's disease was seen in people without the risk factors. This suggests that environmental factors, such as air pollution, may contribute to Alzheimer's disease in patients that cannot be explained by genetics.
“We know that air pollution has negative effects on our health, including our brains,” said Jill Disney, program director for the Alzheimer's Association Georgia Chapter, in a statement. “Studies published during AAIC 2021 were the first to suggest that reducing air pollution is associated with lower risk of dementia and Alzheimer’s disease.”
Disney called for further research in areas of the U.S. with higher levels of pollution, where low-income people and people of color tend to live.
The Chicago-based Alzheimer's Association announced last year that it invested $100 million in dementia research, the largest single-year investment since the nonprofit organization was founded in 1980. In Georgia alone, he was awarded $600,000 to advance research efforts in 2023.
Overall, Georgia has 19 ongoing projects totaling nearly $3.5 million, conducting research including investigating risk factors, care and early detection.
Emory's research was funded by an Alzheimer's Disease Research Center pilot grant through the National Institute on Aging. Huels and the other researchers had no relevant financial interest in the results.
What is “fine particulate matter”?
The Environmental Protection Agency says these particles are so small that they can be inhaled deep into the lungs and into the bloodstream, causing health problems.causing haze to form in some areas of the United States
These particles are composed of solids or droplets that are generally 2.5 micrometers or less in diameter.
How small is 2.5 micrometers? Imagine a strand of hair growing from your head. The average human hair has a diameter of about 70 micrometers, making it 30 times larger than the largest microscopic particle.
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