Is there a link between exposure to air pollution and the risk of dementia?

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Is there a link between exposure to air pollution and the risk of dementia?

Recent studies suggest that long-term exposure to air pollution may be linked to memory and thinking problems, and an increased risk of dementia.

Although at this stage the evidence is not conclusive and more research needs to be undertaken, interesting results have emerged from two research projects.

Published in Neurology a study of 5,330 New York residents reported participants living in areas with higher levels of air pollution had lower scores in memory and thinking at the start of the study. In addition, they had more rapid rates of cognitive decline over time than people living in less polluted areas. However, in a smaller cohort of 1,093 participants, no significant association between air pollution and cognition was found.

In another study of almost 3,000 adults living in Stockholm researchers not only found that higher levels of exposure to air pollutants were associated with increased dementia risk, but also that certain cardiovascular diseases appeared to amplify the association. Details published in JAMA Neurology outline how heart failure and ischemic heart disease both enhanced the dementia risk, while stroke explained almost 50 percent of air pollution-related dementia cases.

These studies investigated the health impacts of two major air pollutants. The first was particulate matter, which is a mixture of solid particles and liquid droplets resulting from the burning of fossil fuels. The second was nitrogen dioxides, which are produced from road traffic exhausts. Both types of pollutant are commonly found in cities around the world. In the above studies, levels were within the range considered safe by regulatory bodies.

The research to date does have some limitations. For example, exposure to air pollution was based on time spent at the residential address, and did not include time spent in traffic or at the workplace. Further research to better understand the impact of air pollution on brain health throughout the lifespan is also required.

Although it may be difficult for someone to reduce their exposure to air pollution, people with cardiovascular diseases who live in polluted areas may require additional support from care providers to both improve their heart health and reduce their risk of dementia.