In a UK study, a causal relationship has been established between air pollution and cognitive decline / dementia. The primary cause is a decline in blood flow to the brain.
Morgantown, Philadelphia-Reading-Camden, PA, New York/Newark, Pittsburgh-New Castle-Weirton, PA rank in the worst in the Northeastern USA.
The worst in PA include Emsworth, Forest Hills, Freedom, Ben Avon, Edgewood, Braddock, Millvale, Carnegie, North Braddock, Sewickley, McKeesport, Bristol, Chester, Norristown, Harrisburg, Hershey, Lancaster, Kutztown, York, Allentown, Freemansburg, Swiftwater, Wilkes-Barre, Altoona, Montoursville, State College, Tioga, Kittanning, Farrel, and Erie.
Cognitive decline, dementia and air pollution
COMEAP reviewed nearly 70 studies in human populations (epidemiological studies) which looked at possible links between air pollution and a decline in mental ability and dementia in older people. They also considered studies which investigated how air pollution might affect the brain.
From this review, it can be concluded that it is likely that air pollution does contribute to these effects. The most likely way this occurs is through effects on the circulation. It is known that air pollutants, particularly small particles, can affect the heart and blood vessels, including to the brain.