Reducing Pollution Emissions May Decrease Life-Long Dementia Risks: Study

Adding to the growing body of evidence linking air pollution to an increased chance of dementia later in life, the findings of a new study have led researchers to call for targeted interventions to address the risk among older adults.

University of Michigan researchers say exposure to a specific type of air pollution, particulate matter (PM), increased the risk of older adults developing dementia or suffering cognitive decline over the next ten years.

Particulate matter is often generated by coal combustion, traffic, and wildfires; which have increased significantly in recent years. Therefore, researchers indicate that selective actions targeting key emission sources could have a substantial impact on the life-long dementia risks, according to findings published this week in the journal JAMA Internal Medicine.

The study involved a review of data from nearly 28,000 participants of the Environmental Predictors of Cognitive Health and Aging study. Researchers included participants with an average age of 61 years old and took study data from the biennial surveys from 1998 to 2016 from the Health and Retirement Study; a nationally representative, population-based cohort study in the U.S.

Researchers included all participants older than 50 who were without dementia at the beginning of the study period, and had available exposure data. Exposure data for 10-year average total PM 2.5 emissions, as well as PM 2.5 emissions from nine different types of sources at participant’s residences, were compiled for each month during follow-up.

According to the findings, a total of 4,100 participants developed dementia during the 10-year follow-up period. Examining the exposure data, researchers determined that higher concentrations of PM 2.5 were linked with greater rates of dementia among participants.

Particulate Matter Air Pollution Sources

PM 2.5 is air pollution with tiny particles of soot, dust, chemicals, and dirt smaller than 2.5 micrometers or 70 times smaller than the width of a single human hair.

Because the particles are so small, it is easy for them to enter the airways and the bloodstream leading to a range of negative health effects, including increased risk of stroke, cardiac arrest, and dementia, even in small amounts of exposure.

When researchers focused on different sources of particulate matter and their links to dementia, they found that PM 2.5 from all sources except dust was linked with increased rates of dementia diagnosis. The strongest associations were linked to emissions from agriculture, traffic, coal combustion, and wildfires.

After controlling for other factors, the risk of dementia from PM 2.5 from wildfires and agriculture was the greatest, the researchers determined.

“Higher residential PM 2.5 levels, especially from agriculture and wildfires, were associated with higher rates of incident dementia, providing further evidence supporting PM 2.5 reduction as a population-based approach to promote healthy cognitive aging,” they wrote.

Air Pollution Dementia Risks

This study is one of many that have raised concerns about the link between air pollution and dementia in recent years.

Research published in 2020 indicated that exposure to air pollution increased a person’s risk of developing several serious neurological disorders, including dementia, Alzheimer’s disease, Parkinson’s disease, and other conditions. Another 2020 study also found that people with pre-existing heart conditions were more likely to develop dementia even at low levels of air pollution exposure.

Other studies have found that people who live near highways and other major roadways face an increased risk of dementia from traffic pollution.

The University of Michigan researchers concluded there is now enough evidence to call for air pollution emission interventions, and targeted revisions to pollution regulations, to help reduce the risk of cognitive impairment in adults.