Fine dust can make the brain shrink and cause cognitive decline, a local study said. The study draws attention because it identified scientifically how air pollution could increase the risks of senile dementia.
On Tuesday, the joint research team led by Professor Kim Chang-soo of the Preventive Medicine Department at Yonsei University College of Medicine said that the higher the concentration of air pollutants, the smaller the brain structures, which harms cognitive function.
Professor Noh Young of Neurology at Gachon University Gil Medical Center and Professor Cho Jae-lim of Preventive Medicine at Yonsei University College of Medicine also participated in the study.
Major air pollutants include fine dust with particulate matter (PM) 10, ultra-fine dust with PM 2.5, and nitrogen dioxide (NO2) emitted from automobiles, aircraft, and ships.
The research team recruited 957 people aged 50 or more who lived in four cities, including the Seoul metropolitan area, from 2014 to 2017. The number of male participants was 427, and that of females, 530. They did not have any history of brain diseases such as dementia, stroke, or Parkinson’s diseases.
Using brain MRI, the researchers measured the subjects’ cortical thickness and subcortical volume. Then, they compared the values with the concentration of air pollutants in the subjects’ residential areas.
The results showed that the higher concentration of air pollutants, the thinner cortical thickness, and the smaller the brain structures such as the hippocampus, basal ganglia, and thalamus.
A 10ug/m3 increase in PM10 was associated with 0.02mm thinner frontal cortices and 0.06mm thinner temporal cortices.
A 10ug/m3 increase in PM2.5 was associated with 0.18mm reduced temporal cortices.
NO2 concentration affected the entire brain. A 10ppb increase in NO2 was associated with 0.01mm thinner total brain cortical thickness. In each area, the frontal lobe and parietal lobe decreased by 0.02mm, the temporal lobe, 0.04mm, and the insular lobe, 0.01mm.
“The area becoming thinner due to exposure to air pollutants is mainly responsible for learning and memory. This area is associated with memory loss in dementia,” said Noh. “A long-term exposure to air pollution accelerates brain aging and increases the risk of dementia even in healthy elderly people with no underlying disease.”