New research offers powerful evidence of a link between air pollution and the risk of developing dementia.
A recent study has found that older women who breathe in air that has been polluted by vehicle exhaust fumes and other fine particulates from other sources are nearly twice as likely to develop dementia. Furthermore, the cognitive effects of air pollution are dramatically more pronounced in women who carry the APOE-e4 gene - this puts them at a higher risk of developing Alzheimer's disease.
A ten year nationwide study, carried out in the United States, explored the cognitive health of women between the ages of 65-79. It found that those who carry the APOE-e4 gene are nearly three times more likely to develop dementia if exposed to high levels of air pollution than those APOE-e4 carriers who are not.
While scientists have always linked air pollution to asthma, lung disease and cardiovascular disease, the negative impact of air pollutants on brain health has only just come to the fore. The aforementioned study provides new insight into how urban smog scrambles the aging brain.
The research looked at a large population of American women, lab mice, and at brain tissue in petri dishes to see if there was a link between cognitive decline and the small particles of pollution that are emitted by motor vehicles, power plants, and the burning of biomass products such as wood.
All three research methods suggested that exposure to high levels of fine air pollutants increases disorientation and memory loss - two classic behavioral signs of dementia.
A study published in 2011 found that those who live near to heavily trafficked roads are way more at risk of developing dementia or having a stroke than those who do not. In 2012, a team led by Alzheimer's disease researcher Dr. Samuel Gandy at Mt. Sinai in New York found that air pollutants induced cell death, inflammation, and the buildup of amyloid protein in the brains of mice.
This new study builds on these findings. This new study estimates that before the EPA (Environmental Protection Agency) decided to set new air pollution standards in 2012, around 21% of new dementia cases and accelerated cognitive decline could be attributed to air pollution.
Air pollution has been on a steady decline ever since 2012. However, Dr. Jiu-Chiuan Chen, an environmental health specialist at USC's Keck school of Medicine, and the study's senior author, has stated that even though there has been a decline in the levels of air pollution over the last five years, it's still not clear whether the current standards are safe for aging brains, or those brains that are genetically vulnerable to Alzheimer's.