New study: Direct link between air pollution and Alzheimer’s

Traffic in the city

Air pollution from traffic might be an important risk factor for vascular dementia and Alzheimer’s disease,according to a new Swedish study that assessed the association between long-term exposure to traffic-related air pollution and dementia incidence in Umeå, a city with a population of about 120,000 in northern Sweden.

Researchers from several faculties of the University of Umeå conducted the study together with the AgingResearch Center of the Karolinska Institute in Stockholm and the Umeå Center for Functional Brain Imaging.

The results uncovered a direct link between car emissions and increased risk of Alzheimer’s disease or vascular dementia. According to the research, people who live in homes exposed more heavily to air pollution run a 40 percent greater risk of developing these diseases than those who live in areas with cleaner air.

15-year study of 2,000 people
The study followed nearly 2,000 Umeå residents over a 15-year period. Those who participated in the study showed no initial signs of memory impairment and took a memory test every five years.

The researchers also estimated the amount of exhaust outside the participant's homes by the number of cars and trucks that ran through the area and measured the levels of air pollution. A land-use regression (LUR) model for Umeå was used to estimate the annual average levels of Nitrogen Oxides (NOx), a commonly used marker of vehicle exhaust. Consideration was given to other factors such as age, education, body mass index, and various lifestyle factors.

16 percent of dementia cases possibly related to traffic pollution
Comparing the air quality of locations where the participants lived, along with their medical data, researchers found a clear pattern. "In total, 16 percent of all the dementia cases in the study might be related to exposure to exhaust," said Bertil Forsberg, Professor of Occupational and Environmental Medicine at the Department ofPublic Health and Clinical Medicine, Umeå University.

“Previous research has linked air pollution to cardiovascular disease, cancer, asthma and respiratory disease,but the new study suggests that very small particles from traffic-related air pollution can also enter the brain through the olfactory nerve and cause direct damage”, Bertil Forsberg commented in an article in DagensNyheter, one of Sweden’s largest daily newspapers.

He also noted that exhaust has also been shown to cause inflammation that affects both the respiratory tract and other organs, which in turn, affects blood circulation in the brain.

The study was published in the Environmental Health Perspectives journal on July 31, 2015. To read the scientific article, click here:


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