On days of heavy air pollution, be it smog or bushfire smoke, we tend to worry about our lungs and throat and the sting in our eyes.
It’s well established, but perhaps less well known in the wider community, that exposure to air pollution in the longer term impedes mental performance, particularly in older people.
These effects include reduced brain volume, cognitive decline and the development of dementia.
Air pollution has also been associated with poor cognition in children and adults. Until now, however, little was known about the effects of short-term exposure to air pollution.
A new study from Columbia University’s Mailman School of Public Health found that smog’s impact on cognitive function shows up over the course of only a few weeks’ exposure.
The good news? The researchers say “these adverse effects were lessened in people taking non-steroidal anti-inflammatory drugs like aspirin”.
How the findings were made
The researchers examined the relationship between exposures to fine particulate matter (PM2.5) and black carbon, and cognitive performance in 954 older white males from the greater Boston area enrolled in the Normative Ageing Study.
Previous research has found that older men and less educated people are the most vulnerable to air pollution’s brain-slowing effects.
Cognitive performance was assessed using the Global Cognitive Function which assesses overall cognitive function – and the Mini-Mental State Examination, a widely used test of cognitive function among the elderly that includes tests of orientation, attention, memory, language and visual-spatial skills.
Air pollution levels were measured from a site in Boston.
Elevated average PM2.5 exposure over 28 days was associated with declines in scores on both tests.
However, men who took aspirin “experienced fewer adverse short-term impacts of air pollution exposures on cognitive health than non-users, though there were no direct associations between recent [aspirin] use and cognitive performance”.
The researchers suggest that non-steroidal anti-inflammatory drugs (NSAIDs), especially aspirin, may moderate neuro-inflammation or changes in blood flow to the brain triggered by inhaling pollution.
“Despite regulations on emissions, short-term spikes in air pollution remain frequent and have the potential to impair health, including at levels below that usually considered hazardous,” says senior author Professor Andrea Baccarelli, chair of the Department of Environmental Health Sciences.
“Taking aspirin or other anti-inflammatory drugs appears to mitigate these effects, although policy changes to further restrict air pollution are still warranted.”
The researchers note that “randomised clinical trials of NSAID use are needed to validate” their protective effects.
In 2019, the same researchers found that aspirin lessened air pollution’s adverse impact on lung function.
Examples of events that would increase someone’s exposure to air pollution over the short term “could include forest fires, smog, second-hand cigarette smoke, charcoal grills, and gridlock traffic”.