Poor air quality can increase the risk of dementia and Alzheimer’s disease.
Xinhui Wang, PhD, assistant professor of research neurology, Department of Neurology, University of Southern California, Los Angeles, and colleagues, have found that reducing exposure to air pollution may slow cognitive decline and decrease the risk of dementia. These findings were presented at the Alzheimer’s Association International Conference (AAIC) 2021.
“The results have implications for individual behaviors, such as avoiding areas with poor air quality, but they also have implications for public policy,” said Wang. “Controlling air quality has great benefits not only for the short-term, for example for pulmonary function or very broadly mortality, but can impact brain function and slow memory function decline, and in the long run may reduce dementia cases.”
The study used a subset of participants from a previous Women’s Health Initiative Memory Study-Epidemiology of Cognitive Health Outcomes (WHIMS-ECHO). The data set included 2232 elderly women aged 74-92 who did not have dementia at the time of enrollment. The team gathered measurements of participants’ cognitive function from 2008 to 2018, which included general cognitive status using the Telephone Interview for Cognitive Status-modified (TICSm) and episodic memory assessed by the telephone-based California Verbal Learning Test (CVLT).
The researchers noted, “We [found] that long-term exposure to air pollution impedes cognitive performance in verbal and math tests. We provide[d] evidence that the effect of air pollution on verbal tests becomes more pronounced as people age, especially for men and the less educated. The damage on the aging brain by air pollution likely imposes substantial health and economic costs, considering that cognitive functioning is critical for the elderly for both running daily errands and making high-stake decisions…This suggests a possible biological connection between air quality and the physical brain changes which define Alzheimer’s disease.”
Claire Sexton, the Alzheimer’s Association director of scientific programs and outreach responded to the study, “We’ve known for some time that air pollution is bad for our brains and overall health, including a connection to amyloid buildup in the brain. But what’s exciting is we’re now seeing data showing that improving air quality may actually reduce the risk of dementia. These data demonstrate the importance of policies and action by federal and local governments, and businesses, that address reducing air pollutants.”
A previous study lead by author Erin Kulick, PhD and colleagues analyzed data from two community sample populations in Manhattan and found that pollution may be linked to cognitive deficits and a sharper rate of cognitive decline. The findings were published in an April 2020 issue of the journal Neurology.
“There are several biological mechanisms through which we believe air pollution impacts the brain, with the strongest evidence surrounding pathways of systematic inflammation and oxidative stress,” Dr. Kulick said. “Both have been investigated in a series of animal studies, and it’s likely that they are working in concert with each other to cause damage to the brain leading to cognitive decline.”