Could living near a busy road increase dementia risk?

A Canadian study claims pollution and road traffic noise could be a factor in your risk of developing dementia.

New research published in The Lancet has suggested there could be a link between living near a major road and your chances of developing dementia.

The population-based cohort study used data from 6.6 million people living in the Canadian province of Ontario between 2001 and 2012.

Researchers were keen to build on previous research from the US and Germany, linking pollution from traffic on major roads with neurodegenerative diseases such as dementia, Parkinson’s disease and multiple sclerosis.

During the study, of the 6.6 million people studied, 243,000 went on to develop dementia, and the risk was greater if they lived close to a major road such as a motorway or A-road.

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

From these figures, the researchers estimated that nearly one in 10 cases of dementia could be linked to living near a major road.

Dr Hong Chen, from Public Health Ontario and one of the report authors, said:

‘Increasing population growth and urbanisation 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 tyre-wear may be involved.

But if this is the case, should everyone pack up and leave the cities? In a word, no. As well as being highly impractical, many dementia experts are quick to point out that the study is still no real confirmation that pollution and traffic noise actually causes dementia.

Dr David Reynolds, Chief Scientific Officer at Alzheimer’s Research UK, explains:

‘There are 850,000 people in the UK living with dementia, and therefore interest in the risk factors driving the condition is high. This research is interesting in its identification of an association between dementia and major roads, but if any causal link exists between these two factors, it can’t be confirmed by this study.

‘Conditions like dementia have multiple risk factors including age and genetics, and other social factors relating to where people live in cities could also be playing a part here. This study has identified major roads and air pollutants from traffic as possible risk factors for dementia, a finding which will need further investigation before any firm conclusions can be drawn about the relative risks of air pollutants for dementia versus other risks such as smoking, lack of exercise or being overweight.’

So, if you live near a busy road, don’t automatically assume you’re going to get Alzheimer’s disease, or feel like there’s nothing else you can do to reduce your risk. A healthy diet, giving up smoking, moderating your drinking, reducing stress and doing exercise are also major factors which can reduce your dementia risk, so focus on those first.

Sources: alzheimersresearchuk.org and bbc.co.uk