A study published in The Lancet medical journal found that people who lived within 50 meters (55 yards) of high-traffic roads had a 7.0 percent higher chance of developing dementia compared to those who lived more than 300 meters away from busy roadways.
Dementia is caused by brain diseases, most commonly Alzheimer's disease, which results in the loss of brain cells and affects memory, thinking, behavior, navigational and spatial abilities and the ability to perform everyday activities. Other causes of dementia include stroke and hypertension.
World Health Organization (WHO) reported that 47.5 million people worldwide have dementia – a syndrome marked by deterioration in memory, thinking, behaviour and the ability to perform everyday activities.
The study , led by Hong Chen from Public Health Ontario, found that long-term exposure to two common pollutants – nitrogen dioxide (NO2) and fine particulates – were associated with dementia but did not account for the full effect.
This suggested that other factors, such as noise or other pollutants, may play a contributing role.
The research did not establish any link between proximity to heavy traffic and other neurological conditions such as Parkinson’s disease or multiple sclerosis.
Some 7.7 million new cases of dementia are reported every year, with Alzheimer’s disease being the most common cause and contributing to 60–70 per cent of cases.
Pollution has long been suspected as playing a role in the development of Alzheimer’s disease but no clear link had been established until now.
“Increasing population growth and urbanisation has 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.”