Nathan Howes
Tue, January 10, 2023
Risk of dementia linked to air pollution exposure, new study says
The health risks associated with air pollution are well-documented, and now, researchers may have found another possible consequence to exposure: Dementia.
Meta-analysis done by Western University researchers has indiciated that higher exposure to a specific type of traffic-related air pollution, called particulate matter, may be tied to an elevated risk of dementia, according to the study recently published in Neurology.
The rate of air pollution exposure for those with and without dementia were compared. Researchers found people who did not develop it had a lower average of daily exposure to fine particulate matter than those who have it.
The risk of dementia increased by three per cent for every one microgram per cubic-metre rise of fine particulate matter exposure.
Researchers examined 17 studies involving more than 91 million people over the age of 40 worldwide. Of those, 5.5 million people, or six per cent, developed dementia.
Cheryl Santa Maria graphic
Researchers at Western University have uncovered a connection between exposure to air pollutants and a greater risk of dementia. (Cheryl Santa Maria/The Weather Network)
"We don't know exactly why there is this relationship between fine particulate matter and dementia," said Janet Martin, professor at Western’s Schulich School of Medicine and Dentistry, in a recent interview with The Weather Network.
The connection between dementia and pollutants
Martin, working alongside Western graduate student Ehasan Abolhasani, gathered data from any country that reported on the relationship between pollutants and dementia, combined it with information from previously published studies and then reviewed each pollutant that could be isolated.
Afterwards, they were able to draw a link between pollutants and the rate of dementia.
"There are a lot of unknowns as to what really is the main mechanism or related mechanisms that lead to the development of dementia," said Martin.
She said the particulate matter fragments are so small they can actually travel down into the smallest parts of your airways and into your alveoli.
"Because they are so small, they can actually enter the bloodstream and evade some of your immune system. We think that is the reason why they are so risky...because they do have a direct entry into the bloodstream. [This] may then have ultimate impacts in terms of the risk of dementia," said Martin.
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But the problem of fine particulate matter can't be completely attributed to fuels, Martin said, noting it is something that is emitted through combustion and chemical processes. Other major sources include wood or crop burning and wildfires.
"In Canada, we have exposure to fine particulate matter that is several folds lower than in some other countries where there is the concentration of population, but also reliance on combustion of other types of fuel or wood burning, or crop burning," said Martin.
How to limit exposure
There is good news when it comes to particulate matter in Canada. Exposure to it has been decreasing over the last decade because regulations have prompted a reduction in emissions from the transport industry and the industrial sector, Martin said. There has also been a drop in crop and wood burning, as well as fuel in our homes.
"Different countries around the world have named different thresholds based on what's feasible to achieve," said Martin. "In Canada, our standards have been on the lower side to be safer than what some [other] countries have named as their maximum exposure."
In terms of deterrence, Martin said the "main message" is that fine particulate matter is emitted through combustion and chemical processes, so you can avoid most of the preventable exposure by having a "very safe" indoor environment where you're not burning items.
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And if you are burning objects, ensure you have a well-ventilated space.
"If the ambient exposure outdoors is high...then it does really become an important factor where those who live in areas of concentrated exposure have safe indoor spaces, which are then protected from the fine particulate matter from the outdoors," said Martin.
She does note, however, that many people don't have a choice on where they live and they lack a "full control over their own exposures."
So, this is where governments and "each of us as contributors" of air pollutants take responsibility for adhering to standards -- by incorporating a local and global mindset of minimizing our emissions, Martin added.
"It's a very serious reduction in the quality of and length of life. Dementia [has an] increasing incidence. It's sort of like that thief in the night that is coming upon our population as we age," said Martin. "It's one of the most important things that we learn to address and prevent, so that we don't have this huge burden of disease as our population ages."
WATCH: The link between worsening mental health and air pollution
What are the next steps?
In a press release, Martin said the Western team plans to further evaluate global dementia trends to see if there is a relationship between policies to reduce air pollutants and downward trends in new cases of dementia.
"We need to now do research on interventions to reduce that fine particulate matter exposure, and to evaluate which interventions actually worked to reduce incidence of dementia into the future," said Martin. "That's one of the most interesting parts of research like this."
"Every intervention comes with potential benefits and maybe some risks and costs. It is the cost and the effort, and the amount of reduction in subsequent dementia, that we would be interested in evaluating."
Thumbnail courtesy of buzbuzzer/ E+/ Getty Images.
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