A recent British study finds that living in areas with a high concentration of air pollution is associated with an increased risk of a diagnosis of dementia among older adults.
The World Health Organization has identified dementia as the seventh leading cause of death in the world. Alzheimer’s disease is the most common form of dementia. The number of people worldwide living with Alzheimer’s is estimated to be 47 million, with projections of tripling by 2050.
The Population Health Research Institute at St. George’s University of London evaluated health records of people living in London to identify a possible correlation between high levels of air pollution and cases of dementia. Using data from 2004, the researchers studied over 100,000 health records of people between the ages of 50 and 79 years old. They then tracked the health of these people – 1.7% of whom were diagnosed with dementia – for the next seven years.
The researchers – led by Iain Carey – found that people in the sample who lived in areas with a concentration of nitrogen dioxide and fine particulates known as PM2.5 were 40 percent more likely to suffer from dementia than those who lived in the least polluted areas. The study also showed that the risk of neurodegenerative diseases increases by 7 percent in the presence of air pollution.
This study was conducted by analysing historical data, instead of a conducting a clinical trial, which means that true causation is harder to pinpoint. Rather, this study shows that there is a correlation between high concentrations of pollution and neurodegenerative diseases. The researchers took other risk factors of dementia like hypertension and obesity into account and still found that air pollution increases the risk of dementia.
The findings show that the chemical byproducts of burning fuel and gasoline contribute to damaging brain function, indicating that urban areas are more prone to brain damage. The researchers point to the significant gains that could be made for the health of the public by diminishing exposure to these pollutants. Air pollution has previously been linked to cardiovascular and respiratory diseases, making reduced exposure crucial.
The small sample size, narrow regional focus and observational analysis could mean that there are other factors that equally or more associated with the risk of dementia. However, similar observational studies have been undertaken in the U.S., Canada and China showing the same findings. These studies have also found links between dementia and living near major roads. This aligns with the pervasiveness of this risk which makes it a real and growing global concern, especially in countries with ageing populations.
Children and babies are particularly vulnerable to air pollution, with studies finding a link to poorer cognitive development. With the youngest and oldest people in the country at risk for brain damage, air pollution has a substantial negative impact on a significant portion of a country’s population.
Activist groups have suggested sustainable solutions to address road traffic problems including affordable and convenient public transport, greater investment in alternative methods of transportation and better infrastructure for alternative transportation options. They have also criticized efforts to reduce car emissions in the future and called for action to be taken immediately.
Our assessment is that the correlation found by the study, along with similar results in other regions, indicates that this is a severe public health threat – one that needs to be addressed with urgency. We feel that raising public awareness about the dangers of pollutants, specifically with regards to dementia, is essential. Additionally, strong regulatory measures by public authorities and decreased reliance on fossil fuels by individuals will help minimize exposure to urban pollutants. We feel that the trend of growing congestion in urban areas requires fast and effective solutions to prevent the widespread affliction of dementia.