Exposure to fine particulate air pollutants (PM2.5) may increase dementia risk, according to a new meta-analysis. The study was published in The BMJ.
Currently, up to 40% of dementia cases may result from modifiable risk factors, including lack of physical activity, poor diet, high alcohol consumption, low levels of cognitive engagement, and air pollution. In the current study, researchers sought to measure the effects of air pollution on dementia risk.
In a press release, Marc Weisskopf, Professor of Environmental Epidemiology and Physiology at Harvard University, lead of the study, said that the findings support the public health importance of limitations to PM2.5 exposure. He added that they could be used by organizations such as the Environmental Protection Agency to strengthen existing limits.
For their meta-analysis, the researchers included 16 studies that explored the relationship between ambient air pollution and the development of dementia over the last past decade. After analyzing the data, they found that each 2 μg/m3 increase in average annual exposure to PM2.5 correlated with a 17% increased risk of developing dementia. They also found an association between nitrogen oxide and nitrogen dioxide and the development of dementia.
"This is a big step in providing actionable data for regulatory agencies and clinicians in terms of making sense of the state of the literature on this hugely important health topic,” said Prof. Weisskopf.
"Exposure to PM2.5 and other air pollutants is modifiable to some extent by personal behaviors- but more importantly through regulation,” he added.
Limitations to the study include insufficient data on the link between exposure to nitrogen oxide and dioxide with dementia. Potentially confounding factors such as noise pollution were also not considered. The researchers noted that future studies will need to analyze critical periods of exposure to pollutants, as well as pollutants other than PM2.5.