In a new study, researchers find air pollution may be linked to an increased risk of developing dementia.
This is a London-based observational study.
Air pollution is a risk factor for heart disease/stroke and respiratory disease, but its potential role in neurodegenerative diseases, such as dementia, isn’t clear.
To try and explore this further, in the current study the researchers used carefully calculated estimates of air and noise pollution levels across Greater London to assess potential links with new dementia diagnoses.
They drew on anonymized patient health records from the Clinical Practice Research Datalink (CPRD). This has been collecting data from participating general practices across the UK since 1987.
The team focused on just under 131,000 patients aged 50 to 79 in 2004.
These people had not been diagnosed with dementia, and they were registered at 75 general practices located within the London orbital M25 motorway.
The researchers estimated these people’s exposure to air pollutants-specifically nitrogen dioxide (NO2), fine particulate matter (PM2.5), and ozone (O3)-as well as proximity to heavy traffic and road noise.
The health of these patients was then tracked for an average of 7 years until a diagnosis of dementia, death, or de-registration from the practice, whichever came first.
The researchers found during the monitoring period, 2181 patients (1.7%) were diagnosed with dementia, including Alzheimer’s disease.
These diagnoses were linked to high levels of NO2 and PM2.5, estimated at the patients’ homes at the start of the monitoring period in 2004.
Those living in areas in the top fifth of NO2 levels ran a 40% heightened risk of being diagnosed with dementia than those living in the bottom fifth.
A similar increase in risk was observed for higher PM2.5 levels.
The researchers suggest that this is an observational study and can’t establish the cause. In addition, findings may be applicable only to London.
However, traffic-related air pollution has been linked to poorer cognitive development in young children, and longtime exposure may cause inflammation and affect brain innate immune responses in early adulthood.
The finding is published in the online journal BMJ Open.
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Source: BMJ Open.