According to a recent study, long-term low-level exposure to air pollution results in an increased risk to dementia, especially for people with pre-existing heart problems.
Published last week in the journal JAMA Neurology, researchers evaluated data on 2,927 participants in the Swedish National Study on Aging and Care in Kungsholmen, a neighborhood in central Stockholm. The participants were at least 60 years old and examined between March 2001 and August 2004.
According to the findings, the risk of dementia increased by as much as 50% for every five years a person lived in the neighborhood. Kungsholmen has consistently low air pollution levels; well below European and United States safety limits for particulate matter.
“Interestingly, we were able to establish harmful effects on human health at levels below current air pollution standards,” lead study author Giulia Grande, a researcher at the Department of Neurobiology, Care Sciences and Society at Karolinska Institutet, said in a press release. “Our findings suggest air pollution does play a role in the development of dementia, and mainly through the intermediate step of cardiovascular disease and especially stroke.”
The reported stated, “Ambient air pollution could also affect the brain indirectly. Air pollution is an established risk factor for cardiovascular health, and it has been shown to be an important trigger of acute myocardial infarction, heart failure, and stroke. Because CVD accelerates cognitive decline and anticipates the onset of dementia, exposure to air pollution might negatively affect cognition, even without directly reaching the brain, by the detrimental effect of CVD.”
In addition to associated long-term exposure to air pollution with dementia, the study found that heart failure and ischemic heart disease appeared to enhance the association between air pollution and dementia, whereas stroke seemed to be an important intermediate condition between the association of air pollution exposure with dementia. With the number of people living with dementia projected to triple in the next 30 years, no curative treatment has been identified to date.
“By 2050, 68% of the world population is expected to live in urban areas, where they are continuously exposed to air pollution,” the report concluded. “Together with the worldwide aging of the population, this poses global challenges when it comes to preventive strategies for dementia. Establishing and characterizing the association between air pollution and dementia has important consequences. We demonstrated an increased association between exposure to higher levels of air pollution and dementia, with stronger association for the last 5 years of exposure. From a policy point of view, this result is encouraging because it might imply that reducing air pollutant levels today could yield better outcomes already in the shorter term, reinforcing the need for appropriately set air quality standards.”