Evidence suggests a link between residential levels of air pollution across London and being diagnosed with dementia, according to researchers.
The evidence of a correlation between air and noise pollution and risk of dementia was recently published in the journal BMJ Open from a trial based across Greater London.
“We found evidence of a positive association between residential levels of air pollution and being diagnosed with dementia”
While the study did not prove the relationship between dementia and pollution, it revealed that where there are high levels of pollution, there are a greater number of dementia diagnosis.
This association cannot be explained by known factors that influence dementia risk, according to the study authors behind the research.
It involved researchers from across the capital at King’s College of London, University of London, St George’s University, and Imperial College London.
Their aimed to investigate whether the incidence of was related to residential levels of air and noise pollution in London, measured using data collected from 75 Greater London primary care practices.
The data from the practices involved comprised the records for 130,978 adults aged from 50 to 79 years of age, who had no history of dementia.
Pollution levels, specifically NO2 and PM2.5, that each participant was exposed to was determined through measuring traffic intensity and night time noise at each post code at the start of 2004.
The researchers said 2,181 subjects (1.7%) were given an incident diagnosis of dementia – 39% mentioning Alzheimer’s disease and 29% vascular dementia.
They found adults living in the highest fifth of NO2 concentration possessed a 40% increased risk of dementia. PM2.5 produced a similar rise in risk for dementia.
Both forms of pollution saw an increase in Alzheimer’s disease among subjects, and all forms of dementia remained unexplainable by other influential factors, such as smoking or diabetes.
Although the way in which pollution increases the risk of dementia is unclear and the factors that lead to dementia are still greatly unknown, the researchers said there would be advances in public health if reducing exposure to pollution did indeed delay the condition.
The study authors said: “We have found evidence of a positive association between residential levels of air pollution across London and being diagnosed with dementia, which is unexplained by known confounding factors.
“Traffic related air pollution has been linked to poorer cognitive development in young children, and continued significant exposure may produce neuroinflammation and altered brain innate immune responses in early adulthood,” they added.