What the air you breathe may be doing to your brain

NEW YORK

- Paula Span and Oona Zenda,Tribune News Service

A haze covers Philadelphia City Hall, caused by smoke from Canada's wildfires.

(File/Tribune News Service)

For years, the two patients had come to the Penn Memory Center at the University of Pennsylvania, where doctors and researchers follow people with cognitive impairment as they age, as well as a group with normal cognition.

Both patients, a man and a woman, had agreed to donate their brains after they died for further research. “An amazing gift,” said Edward Lee, the neuropathologist who directs the brain bank at the university's Perelman School of Medicine. “They were both very dedicated to helping us understand Alzheimer’s disease.” The man, who died at 83 with dementia, had lived in the Center City neighborhood of Philadelphia with hired caregivers. The autopsy showed large amounts of amyloid plaques and tau tangles, the proteins associated with Alzheimer’s disease, spreading through his brain.

Researchers also found infarcts, small spots of damaged tissue, indicating that he had suffered several strokes. By contrast, the woman, who was 84 when she died of brain cancer, “had barely any Alzheimer’s pathology,” Lee said. “We had tested her year after year, and she had no cognitive issues at all.” The man had lived a few blocks from Interstate 676, which slices through downtown Philadelphia. The woman had lived a few miles away in the suburb of Gladwyne, Pennsylvania, surrounded by woods and a country club. The amount of air pollution she was exposed to — specifically, the level of fine particulate matter called PM2.5 — was less than half that of his exposure. Was it a coincidence that he had developed severe Alzheimer’s while she had remained cognitively normal? With increasing evidence that chronic exposure to PM2.5, a neurotoxin, not only damages lungs and hearts but is also associated with dementia, probably not.