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  • Air pollution has been associated with negative effects on cognitive health.
  • However, the effects of exposure at specific points throughout life remain unclear.
  • A new study shows that it is possible to model historical air pollution and link this to cognitive decline over a person’s lifetime.

Researchers have shown that it is, in principle, possible to link a person’s cognitive decline to their exposure to air pollution throughout their life.

This can be achieved by comparing historic air pollution estimates with residential location information.

The research, published in the Journal of Alzheimer’s Disease, may help scientists determine the effects of exposure to air pollution over the course of a person’s life.

The World Health Organization (WHO) report that air pollution kills about 7 million people globally every year.

They provide guidelines about the level of air pollutants that people can safely be exposed to. However, their data suggest that 9 out of 10 people are exposed to environments that exceed these levels.

The WHO explain that air pollution often results from the combustion of fossil fuels. Some main sources of pollutants include vehicles, industry, residential heating and cooking, and agricultural incineration.

According to a recent review in Frontiers in Public Health, air pollution has been linked with both short- and long-term health effects. Some short-term effects include coughing, wheezing, and shortness of breath, while some long-term effects include chronic asthma and cardiovascular disease.

One growing area of research involves the possible link between air pollution and brain health. Researchers have found evidence that exposure to air pollution may reduce a person’s cognitive functioning as they get older and increase their risk of dementia.

However, the longer-term effects of air pollution on brain health, and when in life this exposure is most dangerous, remain unclear.

According to the researchers behind the present study, a general lack of records of air pollution prior to the 1990s and the difficulty of accurately identifying residential locations over long periods constitute challenges to this type of research.

For this reason, the team conducted a feasibility study to see whether it would be possible to track historic air pollution against cognitive decline over the course of a lifetime.

To do this, the researchers used models to estimate historical air pollution rates.

They also drew on data from the Lothian Birth Cohort 1936, a Scottish study that included more than 1,000 participants who had taken a cognitive test in 1947, when they were about 11 years old. The participants then took the same test at ages 70, 76, and 79.

The participants were asked to fill in a lifetime residential questionnaire. 593 participants agreed and 572 were eventually included, with 21 excluded due to missing information.

The researchers identified air pollution estimates for the areas where the participants had lived throughout their lives. They compared this information with the results of the cognitive tests.

The researchers found no significant evidence that air pollution at different points in life was linked with cognitive decline.

They found some limited evidence, however, that exposure to air pollution prior to birth was linked with a decline in cognition from ages 11–70.

However, the researchers highlight the uncertainty of these results, primarily because the modeling of historic air pollution that they used is not very accurate.

For the researchers, the key finding is that it is, in principle, possible to run studies that can make associations between historic air pollution estimates and a person’s cognition.

The key to improving the value of the results would be more accurate air pollution modeling and participant location histories.

The team hopes that further research with more accurate data could help clarify the possible effects of air pollution exposure at various stages on cognitive health.