Living closer than 1000 meters to a major roadway (less than approx. 2/3rd of a mile) increased the risk of dementia by 13-14% compared to people living further away. Dementia included Alzheimers Disease and vascular dementia. This was a large study conducted with 460,901 participants with a mean age of 57. Specific highway air pollution particles were also linked to higher dementia. Each standard deviation increase in nitrogen dioxide, dementia increased by 9% and PM2.5 increased dementia 11%. Brain size changes were also found as described in Read More...
MRI imaging was also done to determine brain changes from higher roadway traffic air pollution. Researchers stated shorter residential distances to major roads was consistently associated with smaller brain volumes. Below is a quote of their findings, "In conclusion, we found that the shorter residential distance to major traffic roads was consistently associated with the higher dementia risk and smaller brain structure volumes. Traffic-related air pollution was identified as the main mediating pathway linking traffic proximity and neurocognitive outcomes, rather than noise pollution. These findings support tackling traffic-related air pollution as the key to preventing dementia onset among people living near heavy traffic. ....................................................
ABSTRACT
Background: Uncertainty exists regarding the operating pathways between near-roadway exposure and dementia incidence. We intend to examine relationships between proximity to major roadways with dementia incidence and brain MRI structure measures, and potential mediation roles of air and noise pollution.
Methods: The cohort study was based on the UK Biobank. Baseline survey was conducted from 2006 to 2010, with linkage to electronic health records conducted for follow-up. Residential distance to major roadways was ascertained residential address postcode. A land use regression model was applied for estimating traffic-related air pollution at residence. Dementia incidence was ascertained using national administrative databases. Brain MRI measures were derived as image-derived phenotypes, including total brain, white matter, gray matter, and peripheral cortical gray matter.
Results: We included 460,901 participants [mean (SD) age: 57.1 (8.1) years; men: 45.7%]. Compared with individuals living >1,000 m from major traffic roads, living ≤1,000 m was associated with a 13% to 14% higher dementia risk, accounting for 10% of dementia cases. Observed association between residential distance and dementia was substantially mediated by traffic-related air pollution, mainly nitrogen dioxide (proportion mediated: 63.6%; 95% CI, 27.0 to 89.2%) and PM2.5 (60.9%, 26.8 to 87.0%). The shorter residential distance was associated with smaller volumes of brain structures, which was also mediated by traffic-related air pollutants. No significant mediation role was observed of noise pollution.
Conclusions: The shorter residential distance to major roads was associated with elevated dementia incidence and smaller brain structure volumes, which was mainly mediated by traffic-related air pollution.