Those living near highways and busy roads have an increased chance of developing dementia -- a syndrome marked by deterioration in memory, thinking, behavior and the ability to perform everyday activities -- a recent study has found.
The research analyzed over 6 million adults living in Ontario, Canada from 2001 to 2012 in a bid to establish a correlation between residential proximity to major roadways and its effect in the onset of dementia, multiple sclerosis and Parkinson's disease.
The study, published in the health journal The Lancet, found that people living within 50 meters (164 feet) of a major road had a 7 percent greater risk of developing dementia than those who didn't.
The level of risk was also found to be proportional to the distance of the residential location from a road. For people living 50 to 100 meters (328 feet) away the risk of developing dementia was 4 percent while for those living 101 to 200 meters (650 feet) away, the risk was 2 percent.
There was no discernable risk of dementia for those living more than 200 meters away from a major road. The study also reported that no link was established between residential proximity to a road and the likelihood of developing Parkinson's disease or multiple sclerosis.
"It is worth pointing out that the numbers of people developing MS and Parkinson's were much smaller than those developing dementia, so (numbers) may not have been large enough to show an effect if there was one," said Prof. Tom Dening, director of the Centre for Old Age and Dementia at the University of Nottingham, reports CNN.
However, researchers involved with the study have stressed that they have proved only an association, and not a direct cause-and effect.
"Our study suggests that busy roads could be a source of environmental stressors that could give rise to the onset of dementia," said Hong Chen with Public Health Ontario, and head of the study.
The onset of the disease is partially accounted for by long-term exposure to nitrogen dioxide and fine particulates -- two common pollutants in urban areas. Other factors such as noise or other pollutants are also believed to play a contributing role, reports AFP.
Over 47.5 million people worldwide have dementia with 7.7 million new cases being reported each year, according to the World Health Organization. Alzheimer's disease is the most common cause, contributing to 60-70 percent of dementia cases.
To help lower the cases of dementia caused by proximity to traffic, "we must implement preventive measures now, rather than take reactive actions decades from now," said Dr. Lilian Calderon-Garciduenas, a professor of biomedical sciences at the University of Montana.