According to a study of more than six million adults in CanadaLiving close to a motorway or highway may increase the risk of developing dementia. Tracking these people over a period of 11 years found a clear link between dementia incidence and living near a main road, comparable to the M1 or M4 in the UK, or major state or interstate highways in the US. Compared with those whose homes were more than 300 metres away from a busy road, people living within 50 metres of heavy traffic had a 7 per cent higher risk of developing dementia. This increase falls to 4 per cent in people living between 50 to 100 metres of a busy road, and 2 per cent in people living between 101 and 200 metres. At greater distances, there was no evidence of a link with the condition.
“Our findings show the closer you live to roads with heavy day-to-day traffic, the greater the risk of developing dementia. With our widespread exposure to traffic and the greater tendency for people to live in cities these days, this has serious public health implications,” says Hong Chen, at Public Health Ontario, who led the study.
The study also found that long-term exposure to nitrogen dioxide and fine particulates – two common components of air pollution – is associated with dementia, but that other factors are likely to be involved too. Other studies have also linked air pollution to dementia risk. However, the study was not able to determine whether roads and air pollution themselves help cause dementia. It’s possible that something else that is associated with these factors may instead be to blame.
