Dementia is a brain disease that affects memory, thinking, and behavior, primarily in older adults but sometimes in younger people too. While many know about lifestyle and genetic factors linked to dementia, a new study suggests that air pollution may also play a role.
Air pollution, already known to harm the lungs and heart, might also affect the brain. Researchers in Stockholm, Sweden, studied over 2,500 older adults living in the city center for up to 12 years to explore this connection.
During the study, 376 participants developed dementia. The researchers focused on tiny air particles called PM2.5, which are invisible to the eye and mainly come from car exhaust and industrial smoke.
The study also examined two “body helpers”—specific substances in the body that play a role in brain function.
One of these helpers comes from foods like meat, fish, milk, beans, and eggs, while the other is made inside our cells and can be converted into the first with the help of certain vitamins. Both substances are important for a healthy brain.
The findings were striking. Participants who developed dementia had been exposed to slightly higher levels of PM2.5 over time compared to those who did not. They also had an imbalance in the levels of the two body helpers in their blood—more of one and less of the other.
Even after accounting for other risk factors like age, gender, smoking, and education, the study found that a small increase in PM2.5 exposure raised the risk of developing dementia by 70%. About half of this increased risk seemed to be tied to the imbalance in the body helpers.
The researchers believe air pollution and the body helpers might interact in a way that damages the brain. However, the exact connection is not yet fully understood.
Air pollution could harm the brain through several mechanisms, and further research is needed to figure out how these substances and environmental factors combine to influence dementia risk.
What this study highlights is the importance of clean air for overall health, including brain health. It also points to the role of diet in supporting brain function, as the foods we eat influence the levels of the body helpers in our blood.
For those concerned about dementia, there are practical steps to consider. Protecting yourself from air pollution by limiting exposure to busy traffic areas or using air purifiers at home can help.
At the same time, maintaining a healthy diet rich in brain-supporting nutrients—such as lean proteins, fish, and vitamin-rich foods—might offer additional protection.
This study is an important starting point in understanding how environmental and dietary factors contribute to dementia risk. While we await further research, focusing on clean air and good nutrition is a proactive way to support brain health.
The findings from this study were published in the journal Neurology. For more on brain health, explore studies about how inflammation might slow cognitive decline or how the MIND diet can help maintain mental sharpness as we age.
If you care about brain health, please read studies about inflammation that may actually slow down cognitive decline in older people, and low vitamin D may speed up cognitive decline.
For more information about brain health, please see recent studies about common exercises that could protect against cognitive decline, and results showing that this MIND diet may protect your cognitive function, prevent dementia.
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