People residing near busy roads have higher rates of Dementia, study suggests.

Research published in the Lancet suggests that people who live near major roads have higher rates of dementia.

The researchers, who followed nearly 2m people in Canadian province of Ontario, between 2001 and 2012, say air pollution or noisy traffic could be contributing to the brain's decline.

The findings needed probing but were "plausible", said UK experts.

The analysis suggests 7-11% of dementia cases within 50m of a major road could be caused by traffic.

"More research to understand this link is needed, particularly into the effects of different aspects of traffic, such as air pollutants and noise," said one of the report authors Dr Hong Chen from Public Health Ontario.

Noise, ultrafine particles, nitrogen oxides and particles from tyre-wear may be involved say researchers.

However, the study looks only at where people diagnosed with dementia live. It cannot prove that the roads are causing the disease.