Are air and noise pollution linked to dementia incidence in England?

Takeaway

• In a sample of 75 general practices across Greater London, being diagnosed with dementia was positively correlated with residential levels of air pollution.
• Positive association was observed between dementia diagnosis and measures of nitrogen dioxide and particulate matter ≤2.5 μm assigned at residential address.

Why this matters

• Vascular dementia and Alzheimer’s disease is reported as the leading cause of death in England and Wales, accounting for 12% of all registered deaths.

Study design

• Retrospective study used data from Clinical Practice Research Datalink to evaluate 130,978 adults (aged, 50–79 years) with no history of dementia or care home residence.
• Funding: UK Natural Environment Research Council and others.

Key results

• During mean follow-up period of 6.9 years, 2181 patients (38.9% Alzheimer’s disease; 29.1% vascular dementia) received a first diagnosis of dementia.
• Patients living in areas with highest vs lowest fifth (>41.5 vs <31.9 μg/m3) of nitrogen dioxide exposure had a marked increase in dementia risk (HR, 1.40; 95% CI, 1.12-1.74).
• After additional adjustiments for multiple pollutants, new dementia diagnosis was positively associated with nitrogen dioxide (aHR, 1.15; 95% CI, 1.04-1.28) and particulate matter ≤2.5 μm (aHR, 1.06; 95% CI, 1.01-1.13) exposure.

Limitations

• Historical data surrounding exposure not available.