A recent study published in the Lancet finds a link between living close to a major road and dementia. The study looked at 2.2 million residents aged 55-85 years in Ontario in Canada. Initially, all of these people were free of neurological diseases. Between 2001 and 2012, 243,611 cases of dementia were identified among the group. A comparison was then made between cases of dementia and how close they lived to a main road.
Increased risk of dementia correlated with the distance people lived from major routes. Those living within 50m of one were 7% more likely to suffer from dementia. Within 51m to 100m the risk was 4% higher and within 101m to 200m, 2% higher. Beyond 200m no clear increase in risk was observed. The study found the risk was higher in urban areas, especially for those in major cities.
It is not entirely clear what is behind the increased risk. Higher concentrations of nitrous oxide and fine particulates from vehicles have been associated with dementia and could be responsible. Other factors such as noise could also play a role.