Exposure to air pollution in childhood is linked to a decline in thinking skills in later life, a study suggests.

Researchers at the University of Edinburgh found greater exposure at the very start of life was linked with a detrimental effect on cognitive skills up to 60 years later.

The study was carried out by examining results of tests the participants took as a child compared with when they were elderly.

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Dr Tom Russ, director of the Alzheimer Scotland Dementia Research Centre, said: “For the first time we have shown the effect that exposure to air pollution very early in life could have on the brain many decades later.

“This is the first step towards understanding the harmful effects of air pollution on the brain and could help reduce the risk of dementia for future generations.”

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The general intelligence of more than 500 people aged approximately 70 years was examined using a test they had all completed at the age of 11 years.

The participants then repeated the same test at the ages of 76 and 79 years.

A record of where each person had lived throughout their life was used to estimate the level of air pollution they had experienced in their early years.

The team used statistical models to analyse the relationship between a person’s exposure to air pollution and their thinking skills in later life.

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They also considered lifestyle factors, such as socio-economic status and smoking.

Findings showed exposure to air pollution in childhood had a small but detectable association with worse cognitive change between the ages of 11 and 70 years.

This study shows it is possible to estimate historical air pollution and explore how this relates to cognitive ability throughout life, according to researchers.

They say until now it has not been possible to explore the impact of early exposure to air pollution on thinking skills in later life because of a lack of data on air pollution levels before the 1990s, when routine monitoring began.