Wildfires and pesticides linked to higher dementia risk, cases on the rise
Wildfires and pesticides linked to higher dementia risk, cases on the rise
The Lifelong Risk of Dementia: The Damaging Effects of Wildfires and Agricultural Air Pollution
Wildfire smoke has been linked to an increased risk of experiencing many health problems. David McNew/Stringer/Getty Images
In a new study from the University of Michigan, researchers have discovered that among all types of air pollution, wildfires and air pollution from agricultural spraying are the most detrimental to brain health. The study found that the tiny particles carried aloft by these two sources, which can be breathed in, are strongly associated with the onset of dementia[^1^].
The study comes at a time when wildfires continue to wreak havoc across North America and the world, with July 2023 being designated the hottest month ever recorded[^1^]. The smoke from these fires can travel great distances, reducing air quality even in areas far removed from the actual conflagrations[^1^]. Additionally, the release of damaging particulates into the air from agricultural spraying further contributes to the worsening air quality over large geographic areas[^1^].
Air quality is measured by the amount of PM2.5 (particulate matter two and a half microns or smaller) in the air. PM2.5 particles are tiny enough to pass through the brain-blood barrier, which typically protects the brain[^1^]. The study estimates that nearly 188,000 new cases of dementia per year in the United States can be attributed to PM2.5 exposure[^1^].
The researchers conducted their analysis using data from the Health and Retirement Study, which followed the cognitive health of over 27,000 individuals over the age of 50 for just over ten years[^1^]. By correlating estimates of PM2.5 exposure with new cases of dementia, they were able to establish the link between air pollution and cognitive health[^1^].
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Why is PM2.5 Harmful to Health?
PM2.5, which is largely invisible to the naked eye, can encompass a broad range of chemicals depending on its source. These tiny particles can enter our body through inhalation and cause inflammation in the lungs. The resulting inflammation factors can then transfer into the bloodstream, potentially contributing to brain inflammation[^1^].
Dr. Boya Yang, the lead author of the study, further explains that PM2.5 may also impact the blood vessels supplying oxygen to the brain. Moreover, some of the smallest PM2.5 particles can even directly enter the brain through the nose[^1^]. This potential neurotoxicity makes PM2.5 an important factor in the development of dementia.
Previous studies have also found a statistical association between PM2.5 and an elevated risk of Alzheimer’s disease and related dementias[^1^]. A recent study even established a causal relationship, showing that the relationship between PM2.5 and cognitive decline is based on quasi-random variations in exposure among more than two million seniors over a decade[^1^].
Wildfires: A Source of Spreading Toxic PM2.5
Wildfires pose a significant threat in terms of air pollution. Anything that serves as fuel for a wildfire, including trees, homes, cars, factories, and stores, can be converted into potentially toxic PM2.5 through heat-related chemical transformations[^1^]. The chemical transformations vary depending on what has been burned and how long the smoke lingers, making the components released during wildfires highly toxic[^1^].
Agricultural Air Pollution: Pesticides as a Primary Source of PM2.5
Agricultural spraying is another major source of PM2.5. Pesticides sprayed onto crops can enter the air and contribute to agricultural air pollution. These treatments often involve neurotoxins to enhance their effectiveness[^1^]. Exposure to PM2.5 from agriculture may be the result of neurotoxins coating particles in the air, which then enter our bodies through inhalation or other pathways[^1^].
Even Non-Extreme Levels of Air Pollution Increase Dementia Risk
What makes the findings of this study even more troubling is that the average levels of PM2.5 associated with the onset of dementia were lower than the National Ambient Air Quality Standard[^1^]. This suggests that cognition may be affected at air pollution levels considered benign by current standards[^1^].
Revising air pollution standards may not be a straightforward solution, however. Air quality is typically measured by estimating the PM2.5 levels in the wider area where individuals reside. This means that exact measurements of the air quality people breathe are not possible[^1^].
Improvements in measuring exposure to PM2.5 and the application of statistical methods to address measurement error will be crucial for future research in this area[^1^]. Dr. Bishop also suggests emphasizing advanced modeling effects for source-specific PM2.5 instead of recalibrating measurement methods[^1^].
The study’s findings highlight the urgent need to address and mitigate the damaging effects of wildfires and agricultural air pollution on brain health. Efforts should focus on reducing the sources of PM2.5 and improving air quality monitoring and measurement techniques to better protect individuals from the lifelong risk of dementia[^1^].
Original article published on medicalnewstoday.com
