Australian researchers have conducted the first global study to find a clear link between air pollution and an increased risk of getting dementia later in life.
The study printed today in the Journal of Alzheimer’s Disease by Dr Ruth Peters at Neuroscience Research Australia (NeuRA), brings together research on people living in regions of Canada, Sweden, Taiwan, United Kingdom and the United States.
The research shows that rates of dementia were more likely when people were exposed over a long period of time to two types of air pollutants; particulate matter 2.5 (PM2.5) and nitrous oxides (NOx).
Particulate matter 2.5 is an airborne mix of solid particles and liquid droplets where each particle is less than 2.5 micrometres wide (the average human hair is 70 micrometres wide). Both types of pollutants are commonly found in cities around the world.
“This study finds mounting evidence that air pollution increases the risk of developing dementia later in life. However, unlike the majority of established dementia risk factors, it is very difficult for someone to reduce their exposure to air pollution, especially if they live somewhere where pollution levels are high,” Dr Peters said.
Researchers believe air pollutants may lead to an increased risk of dementia through two methods. Firstly, by increasing levels of inflammation in our bodies, and secondly by raising the risk of having a stroke – as the rate of developing dementia is fifty times higher in the year after a major stroke.
“This is concerning because the World Health Organisation (WHO) estimates that 91% of the of the world’s population lives in places where air quality exceeds WHO guideline limits. This research shows that government regulation that reduces our exposure to air pollution has a huge potential health and economic benefit,” Dr Peters said.
Dementia is the second leading cause of death of Australians and in 2016 it became the leading cause of death among Australian females. There are currently about 450,000 people living with dementia in Australia. Dementia is estimated to cost Australia $15 billion annually.
This study is published in the Journal of Alzheimer’s Disease as part of a special issue by the International Research Network on Dementia Prevention. This network is led by Professor Kaarin Anstey, Senior Principal Research Scientist at NeuRA and UNSW, who is a co-author on the study with PhD student Nicole Ee and international collaborators.