Researchers at the University of B.C. have found a link between living near highways and an increased risk of several major neurological disorders, including dementia and Parkinson’s disease.
The study, published this week in Environmental Health, found proximity to major roads may also increase the risk for multiple sclerosis and Alzheimer’s diseases, likely because of exposure to more air pollution such as nitrogen dioxide and particulate matter.
Lead author Weiran Yuchi, and a team of researchers at the UBC school of population and public health, analyzed data for 678,000 adults between the ages of 45 and 84 in Metro Vancouver. The subjects were interviewed from 1994 to 1998, and again during a follow-up period from 1999 to 2003.
The researchers concluded that living less than 50 metres from a major road or less than 150 metres from a highway is associated with a higher risk of the neurological disorders, while living near green spaces such as parks and forests reduced risk.
“In our research we found that the green spaces have protective effects against developing the neurological disorders,” said Yuchi, adding that they measured green space using an index of satellite images.
Yuchi said this is the first time UBC researchers have confirmed a link between air pollution and traffic proximity with a higher risk of dementia, Parkinson’s, Alzheimer’s and MS at the population level. There are other epidemiological studies that have reported associations between road proximity and traffic-related air pollution with impaired cognitive function in adults and neurological disorders.
Living near a major road or highway was was associated with a 14 per cent risk for dementia, and seven per cent for Parkinson’s disease.
While the researchers did not identify a percentage for risk for MS and Alzeihmer’s, they did find road proximity was associated with incidence of both.
Yuchi noted that the research does not make recommendations on whether people should be living near highways, but they do suggest more green spaces and accessibility to parks be included in urban planning efforts.
She said their research shows that there is a three to eight per cent reduction in the risk of developing the neurological disorders for those who live near parks or forest.
They do not make recommendations about how to minimize the risk for those who do live near major roadways, and say more research is needed. The study did not account for people who live near roads but spend a significant amount of time in nature hiking or visiting parks.
Michael Brauer, the study’s senior author and professor in the UBC school of population and public health, said, in a UBC statement, that those who live close to a green space are likely to be more physically and socially active, and may benefit from the visual aspects of vegetation.
Brauer added that the findings underscore the importance for city planners to ensure they incorporate greenery and parks when planning and developing residential neighbourhoods.
The study was co-authored by Hind Sbihi, Hugh Davies, and Lillian Tamburic in the UBC school of population and public health.
Researchers are now looking at national data which contains information for 20 per cent of the Canadian population, and they are hoping that this will provide more insight into the association between proximity to highways, air pollution, and neurological disorders.