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Does Air Pollution Cause Alzheimer’s?

We all know that smog and poor air quality are bad for our lungs. Now, clinical studies are indicating air pollution is also bad for our brains. Polluted air can cause a polluted brain. There are many ways you can prevent Alzheimer's, and it looks like one may be making sure you breath clean air.

Research suggests that exposure to air pollution may increase the risk of Alzheimer’s and other forms of cognitive decline. This seems especially true for older people. An aging brain may be more vulnerable to the damage air pollution can cause.

How Air Pollution Effects the Human Brain

Particulate matter in air pollution is considered the most dangerous health risk. And what is particulate matter? It’s a combination of solid and liquid particles suspended in the air which may be quite hazardous.

Particulate matter could be dust, pollen, soot, or smoke. It is generated by wildfires or fossil fuel combustion. Fossil fuels like petroleum and coal release carbon dioxide when they burn. In fact, burning almost anything – oil, gas, firewood, vegetation – creates toxic particulate matter.

Without getting too technical, the air pollutants most hazardous to our health are particulates that scientists refer to as PM2.5. These are ultra-fine, small particulates. They measure less than 10 micrometers in diameter and are especially toxic.

The smaller the particle, the more toxic it is. This is because it can easily find its way into our lungs. When these small polluted particles infiltrate our bodies, they can damage human cells. They can even alter our DNA. We know that Alzheimer’s is caused by cellular damage in the brain, so air pollution may be partially responsible.

An 11-year study with 1400+ elderly women was released last year. It was conducted by researchers at the University of Southern California (USC) Medical School. Many of the women lived in areas with air pollution that exceeded national air quality standards set by the Environmental Protection Agency (EPA). For these women, the risk of dementia almost doubled.

Another recent study published by the U.S. National Academy of Sciences demonstrated that air pollution led to cognitive decline in people as they aged. People in the study who experienced high pollution levels produced lower scores on verbal and math tests. Researchers speculate this was because air pollution tends to damage white matter in the brain. White matter is a tissue in the brain associated with language ability.

Read: Scientists Offer New Way of Looking at Alzheimer's

The Connection Between Air Pollution, Alzheimer’s and Dementia

When something toxic like air pollution enters our body, it permeates our whole system. Studies have linked air pollution to lung cancer, asthma, heart disease, and diabetes, as well as brain damage.

We breathe an estimated 10,000 liters of air into our lungs daily. Our lungs are the main point of entry for toxins. Toxicology experts suspect that airborne pollutants reach the brain through the bloodstream. When blood leaves our lungs, it goes through the heart which pumps it to the rest of the body, including the brain.

Too many airborne toxic particles in our body can lead to inflammation. We know that inflammation in the brain can impact how the brain ages and is linked to Alzheimer’s. The plaques and tangles (beta-amyloid and tau) in a brain riddled with Alzheimer’s may have been caused by air pollution.

Extensive Research Raises More Questions

Ironically, it was man’s best friend – the dog – that first triggered a correlation between polluted air and brain damage. In the early 2000s, a scientist in Mexico City noticed that older dogs living in polluted areas often became confused and disoriented. They couldn’t even recognize their owners. Autopsies showed that these dogs had extensive deposits of beta-amyloid in their brains. These are the same plaques associated with Alzheimer’s.

Many prominent institutions worldwide are now studying the impact of air pollution on Alzheimer’s. Animal testing, human brain imaging, and sophisticated modeling/research techniques are being employed.

A 2012 study, led by Boston University, involved 19,000 retired nurses. The research showed that increased exposure to air pollution led to more cognitive decline in the women.

A Harvard University Medical School study in 2015, studied people living close to a highway with polluted air. The study showed that these people had a smaller cerebral brain volume. This finding held even after adjusting for other factors such as education, smoking and health issues.

Epidemiology is the study of how often diseases occur in different groups of people and why. In 2016, 18 epidemiological studies from around the world were published. All of the studies but one linked high exposure to air pollution with dementia.

Read: How One Protein Could Repair Damage Caused by Alzheimer's

Clean Air for a Healthy Brain

The evidence is mounting that exposure to air pollution can harm the brain. This may increase the risk of Alzheimer’s and accelerate other forms of cognitive decline. Still, experts admit that the correlation remains controversial. In the past decade, research on air pollution as it relates to brain health has increased. But experts say more research is needed to fully understand the link between the two.

According to the World Health Organization, 9 out of 10 people in the world breath bad air. The American Lung Association says that the number in the U.S. is 4 out of 10. These statistics translate into a myriad of health issues, including Alzheimer’s disease.

Hopefully, medical research can conclusively link air pollution with Alzheimer’s. If so, it will be a powerful tool for policymakers worldwide. It will push them to legislate for clean air and mitigate airborne toxins. This knowledge could also help reduce the risk of Alzheimer’s and other dementia-related diseases.

Our editor also recommends you read:

How to Spot the Early Signs of Alzheimer's

What You Can do About Dementia


The impact of exposure to air pollution on cognitive performance

The Polluted Brain

About the Author(s)

An accomplished freelance writer and editor, Cheryl is passionate on how to bolster our resilience in old age and reshape the course of decline. Her compassion and understanding for caregiving stems from acting as a caregiver for her mother, who struggled with dementia, and her father, who suffered from Parkinson’s.

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