Air pollution has long been linked to lung disease, heart problems, and early death. Now, researchers have found more evidence that the air people breathe may also affect how well their brains work as they grow older.
A new study from UC Davis Health and Kaiser Permanente suggests that long-term exposure to tiny air pollution particles may harm an important type of memory that people rely on every day.
The study focused on fine particulate matter known as PM2.5. These particles are extremely small—about 30 times smaller than the width of a human hair.
Because they are so tiny, they can travel deep into the lungs and enter the bloodstream. Scientists have spent years studying how PM2.5 affects physical health, but increasing attention is now being given to its effects on the brain.
Researchers found that people who lived for many years in areas with higher levels of PM2.5 performed worse on tests of semantic memory. Semantic memory is the part of memory that stores general knowledge about the world.
It includes facts, vocabulary, meanings of words, names of objects, and information people learn throughout their lives. This type of memory helps people communicate, understand conversations, and carry out everyday activities.
The findings were published in Alzheimer’s & Dementia: Behavior & Socioeconomics of Aging.
The research used information from the Kaiser Permanente Study of Healthy Aging in African Americans, known as STAR. This ongoing project began in 2017 and was designed to better understand factors that influence healthy brain aging among older Black adults.
The study is especially important because Black Americans experience significantly higher rates of Alzheimer’s disease and other forms of dementia than non-Hispanic White Americans.
The researchers analyzed data from 740 adults between the ages of 53 and 94. They estimated each person’s exposure to PM2.5 by examining air pollution levels at their residential addresses over periods of five, ten, and seventeen years. The team then compared pollution exposure with performance on several cognitive tests.
The results showed a clear pattern. Participants exposed to higher levels of PM2.5 over many years scored lower on tests of semantic memory. The association remained even after researchers accounted for factors such as age, education, income, and marital status.
Interestingly, the researchers did not find a significant link between PM2.5 exposure and two other forms of thinking ability: executive function and verbal episodic memory. Executive function involves planning, decision-making, and problem-solving, while episodic memory involves remembering personal experiences and events.
One of the most striking findings was the size of the effect. The researchers estimated that the impact of long-term PM2.5 exposure on semantic memory was greater than what would normally be expected from ten years of aging.
Scientists believe air pollution may contribute to inflammation and damage inside the body, including the brain. Previous studies have linked PM2.5 exposure to cardiovascular disease, stroke, and a higher risk of dementia. The new findings add to growing evidence that cleaner air may help protect cognitive health as people age.
The study also highlights environmental health disparities. Research from the U.S. Environmental Protection Agency has shown that Black, Latino, and Asian populations are more likely to live in areas with higher levels of particulate pollution. This may contribute to differences in long-term health outcomes.
Researchers note that air pollution is a modifiable risk factor. Unlike age or genetics, pollution levels can be reduced through public policy, environmental regulations, and community planning.
Individuals can also take steps to reduce exposure by monitoring air quality reports, using HEPA air filters indoors, keeping windows closed during poor air quality days, and limiting outdoor activities when pollution levels are high.
If you care about brain health, please read studies about low choline intake linked to higher dementia risk, and how eating nuts can affect your cognitive ability.
For more health information, please see recent studies that blueberry supplements may prevent cognitive decline, and results showing higher magnesium intake could help benefit brain health.
Source: University of California, Davis.
