New research was presented at the 2021 Alzheimer’s Association International Conference (AAIC) showing that cleaner air could reduce an individual’s risk of developing dementia. This follows research indicating that there could be a link between air pollution and the risk of developing dementia, specifically Alzheimer’s disease.
One study was funded by the National Institutes of Health and is known as the Women’s Health Initiative Memory Study-Epidemiology of Cognitive Health Outcomes (WHIMS-ECHO). It was conducted from 2008 until 2018 on women with a range of ages from 74 to 92, with tests administered every year to check if the participants developed dementia. The participants’ home addresses were taken into account, and the levels of air pollution at those locations were estimated using mathematical models. The study found that the level of air quality had improved over the ten years prior to the start of the study. As expected from individuals in this age range, the women in the study did experience a decline in cognitive function. However, the study found that if pollution levels were 10% lower than the Environmental Protection Agency’s set standard, then risk for dementia went down by 14% and 26%. This reduction applied irrespective of the participants’ level of education, the regions in which they lived, or whether they had heart disease. The participants were also seen to experience improved memory and attention levels.
Another study conducted at the University of California San Diego in conjunction with the French Three-City Study observed a link between the reduction of air pollution and a 15% reduction in risk of all-cause dementia, alongside a 17% reduction in risk of Alzheimer’s disease specifically.
Yet another study took a sample of 3,000 people and examined the levels of pollution in the areas in which they lived during the 20 years prior to the study. It found that seniors who were exposed to higher levels of three common air pollutants had higher levels of beta amyloid in their blood. Beta amyloid is a protein fragment that is believed to have a strong connection to the development of Alzheimer’s disease. Abnormal levels of this protein clump together to form plaques that collect between neurons and disrupt cell function. Although research is still ongoing as to the exact nature of this connection, it seems to have a significant amount of influence on whether a person will have Alzheimer’s.
Claire Sexton, the Alzheimer’s Association’s director of scientific programs and outreach, explained that the connection between air pollution and the buildup of amyloids in the brain has been known about for a long time but that the new data is exciting because it indicates that the improvement of air quality may actually reduce the risk of dementia.
These studies are significant because the level of influence of air pollution is a factor that could be changed, in principle, depending on human behavior. Other such factors that can fall within human control and that can have an influence on cognitive decline include blood pressure levels, socialization, diet, exercise, noise, and amount of green space. With some 50 million people around the world living with dementia, these findings are certainly worth monitoring so that we can do whatever is within our power to fight such a horrible disease.