(BBC) People who live near major roads have higher rates of dementia, research published in the Lancet suggests.
As many as 11% of dementia cases in people living within 50m of a major road could be down to traffic, the study suggests.
The researchers, who followed nearly 2m people in Canada over 11 years, say air pollution or noisy traffic could be contributing to the brain’s decline.
UK dementia experts said the findings needed probing but were “plausible”. Nearly 50 million people around the world have dementia.
However, the causes of the disease, that robs people of their memories and brain power, are not understood.
The study in the Lancet followed nearly two million people in the Canadian province of Ontario, between 2001 and 2012.
There were 243,611 cases of dementia diagnosed during that time, but the risk was greatest in those living closest to major roads.
Compared with those living 300m away from a major road the risk was:
- 7% higher within 50m
- 4% higher between 50-100m
- 2% higher between 101-200m
The analysis suggests 7-11% of dementia cases within 50m of a major road could be caused by traffic.
The researchers adjusted the data to account for other risk factors like poverty, obesity, education levels and smoking so these are unlikely to explain the link.