More than 50 million people around the world live with dementia, but the causes of this disease that robs us of our memories and brain power, are not well understood. We received some bad news on this topic this week. As many as 11% of dementia cases in people living within 50 meters of a major road could be caused by pollution and/or traffic noise, a new study suggests. The researchers, who followed nearly 2 million people in Canada over eleven years, say air pollution or noisy traffic could be contributing to the brain’s decline.

This study, published in the Lancet, followed nearly two million people in the Canadian province of Ontario, between 2001 and 2012. There were 243,611 cases of dementia diagnosed during that time, but the risk was greatest in those living closest to major roads.

Compared with those living more than 300 meters away from a major road, the risk was 7% higher within 50 meters, 4% higher between 50-100 meters and 2% higher for those within 200 meters. Researchers adjusted their data to account for other risk factors like poverty, obesity, education levels and smoking so these are unlikely to explain the link.

Pollution particles ‘get into brain’

Dr Hong Chen, from Public Health Ontario, one of the report authors, said:

“Increasing population growth and urbanization have placed many people close to heavy traffic, and with widespread exposure to traffic and growing rates of dementia, even a modest effect from near-road exposure could pose a large public health burden…More research to understand this link is needed, particularly into the effects of different aspects of traffic, such as air pollutants and noise.” 

Add to this the fact that dementia is quickly becoming the leading cause of death, and it becomes harder to deny that living in polluted cities is killing us.

Many studies have focused on the impact of dirty air on the lungs and heart. In early 2016 the World Health Organisation warned that air pollution was leading to as many as three million premature deaths every year. Now, tiny particles of pollution have been discovered inside samples of brain tissue, providing the first evidence that minute particles of what is called magnetite from air pollution, find their way into our brains.

My initial response to this new research is dah! When I first heard about my own serious case of COPD last month, I said to the doctor, “Yes, I’ve had bronchitis in some of the most interesting places.” (Bangkok, Taipei, China, Venice…)

Asia is particularly dirty and I have spent far too much time living there. And Europe isn’t much better, but realistically, most of us breathe polluted air all of the time and somehow believe it isn’t affecting our health. Surprise! It all catches up with you sooner or later.

For decades I have had a personal appreciation of the American Lung Association’s tag line:   “When you can’t breathe, nothing else matters…”