Islamabad, Feb 2: New research strengthens the previously reported link between air pollution and cognitive decline, after finding that exposure to fine particulate matter could significantly raise the risk of developing Alzheimer’s disease and other dementias.
Senior study author Prof. Caleb Finch, of the Leonard Davis School of Gerontology at the University of Southern California (USC), and colleagues say that if their findings apply to the general population, then PM2.5 could account for around a fifth of dementia cases.
PM2.5 are fine particles consisting of solids and liquid droplets that are emitted from sources involving combustion, such as power plants and motor vehicles.
PM2.5 are 2.5 micrometers in diameter or smaller. To put their size into perspective, the diameter of a PM2.5 particle is around 30 times smaller than that of a human hair.
The researchers arrived at their findings by analyzing the data of 3,647 women from 48 U.S. states who were part of the Women’s Health Initiative Memory Study (WHIMS).
All women were aged between 65 and 79 and were free of dementia upon study enrollment. As part of the WHIMS, participants’ cognitive function was assessed annually.
Using data from the EPA, the team estimated the women’s daily PM2.5 exposure at their place of residence.
Compared with women who lived in areas exposed to low PM2.5 levels, those who resided in areas with high PM2.5 levels – defined as levels that that exceeded the EPA’s permissible limit in 2012 (35 micrograms per cubic meter of air) – were found to be at an 81 percent greater risk of global cognitive decline and have a 92 percent increased risk of developing Alzheimer’s disease and other dementias.
The results remained after accounting for numerous confounding factors, including race and ethnicity, socioeconomic status, lifestyle, and the presence of other medical conditions.
The researchers estimated that if their findings ring true among the general population, then exposure to high PM2.5 levels could contribute to approximately 21 percent of dementia cases.
Study co-author Constantinos Sioutas, of the USC Viterbi School of Engineering, explains that the particle concentrators “essentially take the air of a typical urban area and convert it to the air of a freeway or a heavily polluted city like Beijing.”
“We then use these samples to test exposure and assess adverse neurodevelopmental or neurodegenerative health effects,” he adds.