New alarm over toxic air pollution as experts find link to cases of dementia
AIR pollution may be linked to an increased risk of developing dementia, according to research out today.
The study found an association between the condition and exposure to nitrogen dioxide and microscopic particles of pollutants.
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 50 to 79 in 2004, who had not been diagnosed with dementia, registered at 75 general practices within the M25 area.
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, 2181 patients (1.7 per cent) were diagnosed with dementia, 39 per cent of whom had Alzheimer’s disease and 29 per cent of whom had vascular dementia.
These diagnoses were found to be linked to ambient levels of nitrogen dioxide and the microscopic particles 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 per cent higher risk of being diagnosed with dementia than those living in areas with the lowest.
A similar increase was seen with levels of PM2.5 in the research findings, published in the journal BMJ Open.
The links could not be explained by factors known to influence the development of the condition but were more consistent for Alzheimer’s disease than vascular dementia.
The authors said: “Further work is urgently needed to confirm and understand better recent findings linking air pollution to dementia. Our results suggest both regional and urban background pollutants may be as important as near-traffic pollutants.
“The cause of these neurodegenerative diseases is still largely unknown and may be multifactorial. While toxicants from air pollution have several plausible pathways to reach the brain, how and when they may influence neurodegeneration remains speculative.”
Alzheimer’s Research UK described the study as a “growing area of research”, but chief scientific officer Dr David Reynolds added: “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.”
Separate research, presented on Sunday at the European Respiratory Society International Congress in Paris, found children who have green spaces near their homes have fewer respiratory problems such as asthma later in life. Those who are exposed to air pollution are more likely to suffer.