Living near traffic corridors linked to risk of MS, Parkinson's, Alzheimer's disease: UBC study

Researchers at the University of British Columbia have found that living near major roads or highways is linked to an increased risk of neurological disorders, while proximity to parks and green spaces is linked to a decreased risk.

The findings are included in a study published this week in the journal Environmental Health.

"Neurological disorders are one of the leading causes of death and disability, globally, and we know very little about the risk factors associated with neurological disorders," said Weiran Yuchi, the study's lead author and PhD candidate at UBC school of population and public health.

Yuchi's study looked at the neurological health effects of green space, air and noise pollution all together, but she said they made no findings regarding noise pollution.

The researchers found an increase in the incidence of multiple sclerosis, Parkinson's disease, Alzheimer's disease and non-Alzheimer's dementia among those living close to busy roads and highways. 

In the case of Parkinson's, the risk increased by seven per cent among those living close to busy roads and highways. For non-Alzheimer's dementia, the risk rose by 14 per cent.

But on the flip side, the study showed green spaces are associated with a three to eight per cent lower risk of neurological disorders, said Yuchi, who characterized the link as "protective effects."

Study based on Metro Vancouver population

Yuchi said the study doesn't demonstrate that busy roads and green spaces cause the increased and decreased risks, respectively, only that a correlation exists.

In terms of how close to a road one needs to live to fall into the affected population, Yuchi's study used as its measure 50 metres from a major road and 150 metres from a highway. 

The researchers used a data set including nearly 700,000 adults living in Metro Vancouver for their study. They relied on hospital records, prescription information and doctor visits. They then estimated individuals' exposure to air and noise pollution and proximity to green space using their postal codes.

In terms of access to green space, Yuchi said the study used 100 metres as a measure, and beyond the role trees play in creating clean oxygen to breathe, the positive effects could be associated with the likelihood of being more physically active and other benefits of living close to a park. 

"We're not in a position to tell where people should live, but we do suggest that urban planning efforts to increase accessibility to green spaces and to reduce motor vehicle traffic would be beneficial for neurological health at population level," she said.

Yuchi said the study accounted for socio-economic status — things like income and education — as determinants of health, but the researchers didn't look at the effects of those factors directly.

She said she's already working on a similar study with data from across the country, which includes 20 per cent of Canada's population to get an even clearer picture of how environmental conditions relate to the risk of neurological disorders.

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