Exposure to air pollution in childhood is linked to a decline in thinking skills in later life, Edinburgh University researchers have said.
The team tested the general intelligence of more than 500 people aged approximately 70 years 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. 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, the researchers 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,” said Dr Tom Russ, director of the Alzheimer Scotland Dementia Research Centre.
“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.”
Researchers 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.
For this study, researchers used a model called the EMEP4UK atmospheric chemistry transport model to determine pollution levels – known as historical fine particulate matter (PM2.5) concentrations – for the years 1935, 1950, 1970, 1980 and 1990. They combined these historical findings with contemporary modelled data from 2001 to estimate life-course exposure.
A study released earlier this month found that while urban air pollution levels dropped in major cities during the first Covid-19 lockdowns in March 2020, the changes were smaller than expected.