Researchers link pollution and dementia
Swedish researchers have uncovered a direct link between polluted air and dementia. People who live in homes exposed more heavily to pollution run a 40 percent greater risk of developing Alzheimer's disease and vascular dementia than those who live in areas with cleaner air, a study at Umeå University says.

"In total, about 16 percent of all the cases of dementia in the study might have been caused by exposure to pollution," researcher Bertil Forsberg said. The study, published in the journal Environmental Health Perspectives, studied close to 2,000 people over a 15-year span while simultaneously tracking traffic patterns in the northern Swedish city of Umeå. All participants were 55 or older and free of any disease symptoms when the study began. While previous research linked air pollution to cancer, asthma, and respiratory diseases, academics have in recent years begun to probe how air quality affects the brain.
"We know that very small particles can enter the brain through the olfactory nerve and cause direct damage," Forsberg said.

Environmental Health Perspectives: Traffic-Related Air Pollution and Dementia Incidence in Northern Sweden: A Longitudinal Study