People who live within 50 metres of high-traffic roads have a 7 per cent higher likelihood of dementia than those who live more than 300 meters away from busy roads.
As part of the study, researchers examined data relating to more than 6.5 million Ontario residents aged 20-85 years, to investigate the correlation between living close to major roads and risk for dementia, Parkinson's disease and multiple sclerosis.
While there was no correlation between major traffic proximity and Parkinson's disease or multiple sclerosis, they did identified a significant link between traffic proximity and dementia risk. The risk was highest for those living closest to high traffic roads and dropped to 4 per cent if people lived 50-100 metres from major traffic, and to 2 per cent if they lived within 101-200 metres. At over 200 metres, there was no elevated risk of dementia.
Writing in The Lancet, the authors said, while the mechanisms through which traffic exposure might affect brain health are unknown, systemic inflammation arising from traffic-related air pollution is probably important.