Exposure to air pollution and risk of incident dementia in the UK Biobank

Background: Air pollution may cause inflammatory and oxidative stress damage to the brain, leading to neuro-degenerative disease. The association between air pollution and dementia, and modification by apolipoprotein E genotype 4 (APOE-epsilon 4) has yet to be fully investigated.Objectives: To examine associations of air pollution with three types of incident dementias (Alzheimer's disease (AD), frontotemporal dementia (FTD), and vascular dementia (VAD)), and their potential modification by APOE-epsilon 4 genotype.Methods: The UK Biobank enrolled > 500,000 participants (2006-2010) with ongoing follow-up. We used annual averages of air pollution (PM2.5, PM10, PM2.5-10, PM2.5absorbance, NO2, NOX) for 2010 scaled to interquartile ranges (IQR). We included individuals aged >= 60 years, with no dementia diagnosis prior to January 1, 2010. Time to incident dementia and follow-up time were reported from baseline (January 01, 2010) to last censor event (death, last hospitalization, or loss to follow-up). Cox proportional hazard ratios (HR) and 95% confidence in-tervals (95% CI) were calculated to estimate the association of air pollutants and incident dementia, and modification of these associations by APOE-epsilon 4.Results: Our sample included 187,194 individuals (including N = 680 AD, N = 377 VAD, N = 63 FTD) with a mean follow-up of 7.04 years. We observed consistent associations of PM2.5 with greater risk of all-cause de-mentia (HR = 1.17, 95% CI: 1.10, 1.24) and AD (HR = 1.17, 95% CI: 1.06, 1.29). NO2 was also associated with greater risk of any incident dementia (HR = 1.18, 95% CI: 1.10, 1.25), AD (HR = 1.15, 95% CI: 1.04, 1.28) and VAD (HR = 1.18, 95% CI: 1.03, 1.35). APOE-epsilon 4 did not modify the association between any air pollutants and dementia.Discussion: PM2.5 and NO2 levels were associated with several types of dementia, and these associations were not modified by APOE-epsilon 4. Findings from the UK Biobank support and extend to other epidemiological evidence for the potential association of air pollutants with detrimental brain health during aging.

Automated summary

The study found that air pollutants PM2.5 and NO2 were associated with multiple types of dementia, while the APOE-epsilon 4 genotype did not modify these associations.