Dementia diagnosis 'linked to air pollution'

20 September 2018 08:42

Living in areas with high levels of air pollution could be linked to an increased risk of dementia

Living in areas with high levels of air pollution could be linked to an increased risk of dementia

Living in areas with high levels of air pollution could be linked to an increased risk of dementia, new research suggests.

In a study published in the journal BMJ Open, researchers focusing on London found an association between the neurodegenerative condition and exposure to nitrogen dioxide and microscopic particles known as PM2.5.

In response to the study, Alzheimer's Research UK described the findings as a "growing area of research" but said results should be treated with caution.

Diagnosed

Researchers from the University of London, Imperial College and King's College London used anonymous patient health records from the Clinical Practice Research Datalink, which collects data from GP practices.

They focused on 131,000 patients aged between 50 and 79 in 2004, who had not been diagnosed with dementia, registered at 75 general practices within the M25.

The health of the patients was tracked for an average of seven years, until they were diagnosed with dementia, died or left their GP practice.

Between 2005 and 2013, a total of 2181 patients (1.7%) were diagnosed with dementia, 39% of whom had Alzheimer's disease and 29% of whom had vascular dementia.

These diagnoses were found to be linked to ambient levels of nitrogen dioxide and PM2.5, based on estimates taken near the homes of patients in 2004.

Those living in areas with the top fifth of nitrogen dioxide levels had a 40% increased risk of being diagnosed with dementia compared with those living in areas with the lowest, the researchers said.

A similar increase was seen with levels of PM2.5, they added.

Symptoms

Dr David Reynolds, chief scientific officer at Alzheimer's Research UK, warned the latest study does not show cause and effect.

He said: "While the researchers tried to account for factors like wealth, heart disease and other potential explanations for differences in dementia rates across the capital, it is difficult to rule out other explanations for the findings.

"The diseases that cause dementia can begin in the brain up to 20 years before symptoms start to show.

"We don't know where people in this study lived in the two decades before their dementia diagnosis, so we have to be cautious about how we interpret these results.

"The link between air pollution and dementia risk is a growing area of research. This study highlights the importance of further studies that look into exposure to pollution over a longer period of time, and investigate the possible biological mechanisms underlying this link."

Last year, a study published in The Lancet medical journal suggested living close to a busy road increases the risk of Alzheimer's and other forms of dementia.

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