Living near a major road could increase the chance of developing dementia, according to a study.

The survey of 7 million people in Canada found rates rose by over 12 percent among those close to busy routes.

The findings are backed up by recent studies suggesting that long-term exposure to two common traffic pollutants - nitrogen dioxide and sooty particles generated by diesel engines - may contribute to brain shrinkage and mental impairment.

Doctor Ray Copes worked on the study - and says it could help beat a disease that's incurable: