According to a recent study, people who live near major roads have higher rates of dementia.
The study, published in the Lancet, suggests that as many as 11% of dementia cases in people living within 50m of a major road could be down to traffic.
The researchers, who followed nearly 2 million people in Ontario, Canada, over 11 years (from 2001 to 2012), say air pollution or noisy traffic could be contributing to the brain’s decline.
There were 243,611 cases of dementia diagnosed during that time, but the risk was greatest in those living closest to major roads.
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.
One of the study authors, Dr. Hong Chen, from Public Health Ontario, said: “Increasing population growth and urbanization have placed many people close to heavy traffic, and with widespread exposure to traffic and growing rates of dementia, even a modest effect from near-road exposure could pose a large public health burden.
“More research to understand this link is needed, particularly into the effects of different aspects of traffic, such as air pollutants and noise.”
The researchers suggest noise, ultrafine particles, nitrogen oxides and particles from tire-wear may be involved.
However, the study looks only at where people diagnosed with dementia live. It cannot prove that the roads are causing the disease.
Nearly 50 million people around the world are diagnosed with dementia.
However, the causes of the disease, that robs people of their memories and brain power, are not understood.
The best advice to reduce the risk of dementia is to do the things that we know are healthy for the rest of the body – stop smoking, exercise and eat healthily.