MADRID.- Exposure to Fine Airborne Pollutants (PM2.5) may increase the risk of dementia, according to a new meta-analysis from the Harvard TH Chan School of Public Health (USA) published by researchers in The BMJ.
“This is a major step in providing regulators and clinicians with data to understand the state of the literature on this critical health topic. Our results support the public health importance of such a measure.says Marc Weisskopf, lead author and Cecil K. and Philip Drinker Professor of Environmental Epidemiology and Physiology.
The study is the first systematic review and meta-analysis to use the new ROBINS-E-Tool (Risk of Bias In Non-Randomized Studies of Exposure), which looks at bias in environmental studies in more detail than other assessment approaches.
It is also the first to include recent studies using “active case detection.”a method in which entire study populations were screened, followed by face-to-face assessment for dementia in subjects who did not have dementia at baseline.
There are currently more than 57 million people living with dementia worldwide and it is estimated that this is the case This number will increase to 153 million by 2050. It is assumed that up to 40% of these cases are related to potentially modifiable risk factorssuch as exposure to air pollutants.
Weisskopf and her co-authors Elissa Wilker, researcher at the Harvard Chan Center for Environmental Health-NIEHS, and Marwa Osman, graduate student in the Biological Sciences in Public Health program, analyzed more than 2000 studies and identified 51 cases assessing an association between air pollution and clinical dementia, all published within the last decade.
These studies were assessed using ROBINS-E and for bias 16 of them met the criteria for the meta-analysis. Most research focused on PM2.5, with nitrogen dioxide and nitrogen oxides being the second most studied pollutants. Of the studies used in the meta-analysis, nine used active case finding.
Researchers found consistent evidence of a link between PM2.5 and dementiaeven when annual exposure was less than the EPA’s current annual standard of 12 micrograms per cubic meter of air (micrograms/m3).
In particular, Among the studies using active case finding, researchers found a 17% increased risk of developing dementia per 2 micrograms/m3 Increase in average annual exposure to PM2.5. They also found evidence suggesting a link between PM2.5 and dementia.
They also found evidence of associations between dementia and nitric oxide (5% increased risk per 10 microgram/m3 increase in annual exposure) and nitrogen dioxide (2% increased risk per 10 microgram/m3 increase in annual exposure), although the data was more limited.
The researchers found that the estimated association of air pollution with risk of dementia is lower than that of other risk factors such as education and smoking. However, due to the number of people exposed to air pollution, the health impacts could be significant at a population level.
“Given the enormous number of dementia cases, identifying modifiable risk factors to reduce the burden of the disease would have enormous personal and societal implications. Exposure to PM2.5 and other air pollutants can be modified to some extent by personal behavior, but regulation is most important,” Weisskopf said.
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