Air pollution and dementia

Researchers from Public Health, Ontario, Canada in collaboration with Canadian universities and Health Canada examined the link between residential proximity to major roads and the incidence of dementia.  The study, published in the Lancet looked at the risk of long term exposure to nitrogen dioxide and fine particulate matter.  The study followed 6.6 million people in Ontario, aged between 20 and 85 for 10 years.  Researchers looked at 3 major neurodegenerative diseases, dementia, Parkinson's disease and multiple sclerosis.  Researchers found no link to living next to a busy road and developing Parkinson's or multiple sclerosis, however dementia was found to be more common among people who lived closer to busy roads.  

The study which took into account the general health, wealth, education and social status of the participants found those living within 50 metres of a busy road had a 7% higher risk of developing dementia, 4% higher at 50-100 metres and 2% at 101-200 metres.  Those who lived within 50 metres of a busy road and did not move house for the duration of the study were found to be at a 12% higher risk of developing dementia.

Previous studies have linked air pollution and traffic noise to reduced density of white matter (connective tissue in the brain), another study found magnetic nano particles from air pollution in the brains of deceased dementia sufferers.