EMBARGOED FOR RELEASE UNTIL 4 PM ET, February 21, 2024
Air Pollution Linked to More Signs of Alzheimer鈥檚 in Brain
MINNEAPOLIS 鈥 People with higher exposure to traffic-related air pollution were more likely to have high amounts of amyloid plaques in their brains associated with Alzheimer鈥檚 disease after death, according to a study published in the February 21, 2024, online issue of , the medical journal of the 好色先生. Researchers looked at fine particulate matter, PM2.5, which consists of pollutant particles of less than 2.5 microns in diameter suspended in air. The study does not prove that air pollution causes more amyloid plaques in the brain. It only shows an association. 鈥淭hese results add to the evidence that fine particulate matter from traffic-related air pollution affects the amount of amyloid plaque in the brain,鈥 said study author Anke Huels, PhD, of Emory University in Atlanta. 鈥淢ore research is needed to investigate the mechanisms behind this link.鈥 For the study, researchers examined the brain tissue of 224 people who agreed to donate their brains at death to advance research on dementia. The people had died at an average age of 76. Researchers looked at the traffic-related air pollution exposure based on the people鈥檚 home address in the Atlanta area at the time of death. Traffic-related PM2.5 concentrations are a major source of ambient pollution in urban areas like the metro-Atlanta area where most donors lived. The average level of exposure in the year before death was 1.32 micrograms per cubic meter (碌g/m3) and 1.35 碌g/m3 in the three years before death. Researchers then compared pollution exposures to measures of the signs of Alzheimer鈥檚 disease in the brain: amyloid plaques and tau tangles. They found that people with higher exposures to air pollution one and three years before death were more likely to have higher levels of amyloid plaques in their brains. People with 1 碌g/m3 higher PM2.5 exposure in the year before death were nearly twice as likely to have higher levels of plaques, while those with higher exposure in the three years before death were 87% more likely to have higher levels of plaques. Researchers also looked at whether having the main gene variant associated with Alzheimer鈥檚 disease, APOE e4, had any effect on the relationship between air pollution and signs of Alzheimer鈥檚 in the brain. They found that the strongest relationship between air pollution and signs of Alzheimer鈥檚 was among those without the gene variant. 鈥淭his suggests that environmental factors such as air pollution could be a contributing factor to Alzheimer鈥檚 in patients in which the disease cannot be explained by genetics,鈥 Huels said. A limitation of the study is that researchers only had the home address of people at the time of their death for measuring air pollution, so it鈥檚 possible that pollution exposure may have been misclassified. The study also involved mainly white people who were highly educated, so the results may not be representative of other populations. The study was supported by the HERCULES Pilot Project, Goizueta Alzheimer鈥檚 Disease Research Center and the Rollins School of Public Health Dean鈥檚 Pilot and Innovation Grant. Learn more about dementia at , home of the 好色先生鈥檚 free patient and caregiver magazine focused on the intersection of neurologic disease and brain health. Follow Brain & Life庐 on , and . When posting to social media channels about this research, we encourage you to use the hashtags #Neurology and #AANscience.