Air pollution linked to increased risk of dementia, heart disease: Study

People continuously exposed to air pollution are at an increased risk of the neurological condition dementia, according to a study which says the risk is especially high among those suffering from heart diseases.

Researchers, including those from Karolinska Institutet in Sweden, said such patients with cardiovascular diseases who live in polluted environments may require additional support from care providers to prevent dementia, which is characterised by impairment of brain function.

According to the study, published in the journal JAMA Neurology, the number of people living with dementia is projected to triple in the next 30 years.

With no curative treatment identified yet, it said the search for protective factors remain a public health priority.

In the current study, the researchers assessed the link between long-term exposure to air pollution and dementia and what role cardiovascular diseases (CVD) play in that association.

They studied almost 3,000 adults with an average age of 74, and followed them for up to 11 years.

Of the 3000 individuals, the scientists said 364 people developed dementia.

They said the last five years of exposure was significantly related to the risk of developing the neurological condition.

"Interestingly, we were able to establish harmful effects on human health at levels below current air pollution standards," said first author of the study, Giulia Grande from Karolinska Institutet.

"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," Grande said.

According to the researchers, exposure to pollution earlier in life seemed less important than those in the last five years.

They said heart failure and ischemic heart disease both enhanced the dementia risk, and stroke explained almost 50 percent of air pollution-related dementia cases.

"Air pollution is an established risk factor for cardiovascular health and because CVD accelerates cognitive decline, we believe exposure to air pollution might negatively affect cognition indirectly," Giulia Grande said.

"Virtually all of the association of air pollution with dementia seemed to be through the presence or the development of CVD, adding more reason to reduce emissions and optimise treatment of concurrent CVD and related risk factors, particularly for people living in the most polluted areas of our cities," she added.