Living near a busy road increases risk of dementia, study reveals

New research published in the journal The Lancet has revealed that people living in close proximity to a main road have an increased risk of developing dementia, a condition currently affecting 850,000 people in the UK.

According to Canadian researchers, around one in ten cases of dementia can be linked to residents living near a major road, including an A road and motorway.

The study is the first to extend findings from previous research in the US and Germany that suggested pollution from traffic on major roads could be linked to neurodegenerative diseases.

Lead scientist Dr Hong Chen, from Public Health Ontario, said: “Our findings show the closer you live to roads with heavy day-to-day traffic, the greater the risk of developing dementia. With our widespread exposure to traffic and the greater tendency for people to live in cities these days, this has serious public health implications.

“Increasing population growth and urbanisation has 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 study monitored 6.6m adults aged between 20 and 85 living in Ontario, Canada from 2001 to 2012, using postcodes to determine a person’s proximity to major roads. The cohort’s medical records were also examined to identify whether anyone developed dementia, Parkinson’s disease or multiple sclerosis.

Over the ten-year study, more than 243,000 people developed dementia, 31,500 people developed Parkinson’s disease and 9,250 people developed Multiple Sclerosis (MS).

Researchers observed that 95 per cent of participants lived within one kilometre of a major road such as a motorway or A road, with half living less than 200 meters away.

They found those who lived within 50 meters of a major road had a seven per cent higher risk of developing dementia, compared to people who lived more than 200 meters away who had no increase in their risk.

However, the study did not discover any link to living near a major road and the development of either Multiple Sclerosis or Parkinson’s disease.

Dr David Reynolds, chief scientific officer at Alzheimer’s Research UK, said: “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.

“Studies like this are valuable in revealing new factors that could be implicated in Alzheimer’s disease and other dementias and opening new avenues for further research. Alzheimer’s Research UK is funding research focusing on reducing the risk factors surrounding dementia, and is dedicated to finding a way of preventing or slowing down the progression of this devastating condition.”