Are you a country or city mouse? Do you prefer the pure, fresh air of open wildlands? Or maybe you need a solid cloud of city smog in order to get your lungs going. All you country folk can put your hands out for a celebratory toast because this past (2021) Alzheimer’s Association International Conference included three research presentations demonstrating a link between pollution and brain health. On the whole, the studies showed that living in areas with lower pollution levels can reduce your risk of developing dementia.
What is dementia?
Dementia is a group of neurological disorders that affect brain function to the point that it disrupts daily living. Dementia can bring about many cognitive, psychological, and personality changes. Patients with dementia can suffer from extreme memory loss, motor difficulties, and paranoia, along with many other symptoms that show a decline in cognitive function. The most well-known form of dementia is Alzheimer’s disease.
How do you measure pollution?
Just as researchers may use centimeters or kilometers to measure distance, or smiles and positive comments to measure happiness, there are a number of ways to measure air quality.
Particulate matter (PM) is a mixture of particles found in the air. It includes solid particles such as dust, dirt, soot, and liquid droplets. Particles can be either visible or invisible to the naked eyes. Sizes of PM include:
- PM2.5 : The notation for fine inhalable particles. They are PMs with a diameter of 2.5 micrometers or less
- PM10 : The notation for inhalable particles which are 10 micrometers or smaller in diameter.
The higher the PM level, the worse the air quality.
NO2 is the chemical formula for nitrogen dioxide, a gaseous pollutant released when coal, oil, gas, or diesel are burned. It occurs most in places with high vehicle traffic.
Study 1: What impact can pollution have on neurological health?
A study led by Xinhui Wang from the University of Southern California, looked at a group of women (aged 74-92) in the U.S. from the National Institutes of Health-funded Women’s Health Initiative Memory Study-Epidemiology of Cognitive Health Outcomes (WHIMS-ECHO). At the beginning of the study, the women did not have dementia. To keep track of their cognitive functions, tests were annually administered to the participants from 2008 to 2018 to assess whether they had begun to develop dementia.
Researchers evaluated the level of air pollution in the participants’ residential locations and compared that with their level of cognitive function during the study period. They found that the participants living in areas with lower PM2.5 and NO2 levels were 14-26% less likely to develop dementia. Women from these areas also benefited from greater cognitive function and memory, regardless of age, level of education, geographic region, and presence of cardiovascular disease.
Study 2. Air quality impacts the brain health of French elderly
Noemie Letellier from the University of California found similar results in a study conducted in conjunction with the French Three-City Study. The study included 7,000 participants aged 65 or older. The researchers discovered that lower air pollutants offer a 15% decreased risk of all-cause dementia and a 17% reduced risk of Alzheimer’s disease for every microgram of gaseous pollutant per cubic meter of air (μg/m3) decrease in PM2.5.
Study 3 Beta amyloid plaque buildup associated with long-term exposure to air pollution
Beta amyloid plaques are a type of protein residue found in the brains of Alzheimer’s patients. While it’s not known exactly how the plaque contributes to the development of the disease, the amount and quality of beta amyloid can indicate the seriousness of the disease.
Previous research discovered a link between beta amyloid plaque and air pollution. However, Doctoral Student Christina Park of the University of Washington wanted to understand the long-term effects air pollution could have on plaque levels. She and her team evaluated more than 3000 participants of the Ginkgo Evaluation of Memory Study. The researchers examined the participants’ exposure to PM2.5, PM10, and NO2, based on their residential location, and compared that to the level of Aβ1-40 (a major component of plaques) in their blood. Higher Aβ1-40 levels indicate higher levels of beta amyloid plaque. The study did find a link between exposure to air pollutants and high levels of Aβ1-40, indicating that pollution can contribute to the development of dementia.
The harmful effects of pollution is global knowledge, integrated into our general awareness from our regular media sources. Pollution is bad for the environment. Pollution is bad for our lungs. Pollution is harmful to animals. It should be no surprise that pollution is also bad for our brains. These three studies offer evidence that pollution can increase the risk of developing dementia in the older population.
Dementia is a debilitating and terrifying condition. With this data, we are now better prepared to face it. We can make better decisions to protect ourselves and slow down its development. Policy makers and urban planners can use this information to create healthier city structures. The average citizen can consider pollution’s impact on dementia when thinking about where to move, especially in older populations. Is it better to be closer to the grandkids in the city? Or to finally move out to the old cabin for some peace and quiet? But before making any major decisions, have a long sit down, carefully think through it all, and take a deep breath of fresh air.
Written by Chani Bonner
References
- Dementia – Overview
- Alzheimer’s – Overview
- Particulate Matter (PM) Basics
- Nitrogen Dioxide
- Association of improved air quality with lower dementia risk in older women
- Long-term exposure to ambient air pollution and risk of dementia: Results of the prospective Three-City Study
- Alzheimer’s Disease and the β-Amyloid Peptide
- The Ginkgo Evaluation of Memory (GEM) Study
- Improving Air Quality May Improve Cognitive Function and Reduce Dementia Risk
