Air quality linked to dementia, cardiovascular disease

People continuously exposed to air pollution may be at increased risk for dementia, and the risk is even higher for those who also diagnosed with a cardiovascular disease, according to a new study by the Karolinska Institutet in Sweden and published in the journal JAMA Neurology.

In this study, researchers examined the link between long-term exposure to air pollution and dementia and what role cardiovascular diseases play in that association. Almost 3,000 adults with an average age of 74 and living in the Kungsholmen district in central Stockholm were followed for up to 11 years. Of those, 364 people developed dementia. The annual average level of particulate matter 2.5 microns or less in width (PM2.5) are considered low compared to international standards.

For the last five years of exposure, the risk of dementia increased by more than 50 percent per interquartile range (IQR) difference in mean PM2.5 levels and by 14 percent per IQR in nitrogen oxide. Earlier exposures seemed less important. Heart failure and ischemic heart disease both enhanced the dementia risk and stroke explained almost 50 percent of air pollution-related dementia cases, according to the researchers.

The number of people living with dementia is projected to triple in the next 30 years. No curative treatment has been identified and the search for modifiable risk and protective factors remains a public health priority. Recent studies have linked both cardiovascular disease and air pollution to the development of dementia, but findings on the air pollution-link have been scarce and inconsistent.

Patients with cardiovascular diseases who live in polluted environments may require additional support from care providers to prevent dementia, according to the researchers.