Spikes in air pollution could speed up cognitive decline in elderly men

Exposure to higher levels of air pollution could cause cognitive decline in older men to speed up, a new study has discovered. Even if the spike is relatively short, it could have a negative impact on the brain function of males over 70, Peking University has found.

In a study of 1,000 men with an average age of 70 in Boston in the US, the researchers noted poorer recall and reaction times when pollution levels were increased 28 days before being tested. They also observed those on anti-inflammatory drugs including aspirin were less negatively affected.

Memory, attention and learning tests were performed with the men over time to determine how their cognitive function varied. The average levels of fine particulate matter (PM2.5) in the air was also assessed to investigate a possible link.

It revealed that even small increases in PM2.5 could be linked to cognitive decline, which is associated with dementia. The scientists have described the findings as ‘startling’, as the difference is noticeable at levels below those usually defined as dangerous.

The World Health Organization's (WHO) recommended air quality target stands at 10μg per metre cubed (m3), but the levels recorded in the study were on average at around 10.13μg. In Britain, the PM2.5 concentration for 2019 was recorded at an average of 10.5µg per m3.

While the latest study builds on a large amount of research linking air pollution to a decline in brain function, it’s among the first to demonstrate short-term damage. The researchers didn’t look at the reasons for the link, just that there appears to be one.

PM2.5 is the finest type of air pollution and is mainly the result of exhaust fumes from vehicles. Scientists have previously speculated that these tiny particles are capable of reaching the brain, where they trigger inflammation and damage neurons, resulting in the cognitive decline that has been observed.

Professor Joanne Ryan and Dr Alice Owen from Monash University in Melbourne in Australia commented on the study for the MailOnline. They said: “The findings were quite startling. Even relatively small increases in the levels of PM2.5 in the three to four weeks prior to testing were associated with consistently worse cognitive performance.”

They added that Boston, where the study was conducted, does not have the biggest air pollution problem when compared to other cities in the world. Since significant detrimental effects of air pollution on cognition were noted here, the issue could be more severe in other locations.

Further to the impact of air pollution, academics were also keen to see if taking anti-inflammatories mitigated the effects. They saw that those participants on these common drugs exhibited just a small drop in their cognitive test scores as pollution levels rose.

Professor Ryan and Dr Owen said: “The findings provide a tantalising possibility of better understanding the role of air pollution on cognitive health, and more research into the underlying mechanisms of NSAIDs’ [anti-inflammatory drugs] potential protective effects is urgently needed.”