Advisers to the UK government suggest that air pollution may be linked to dementia and cognitive decline in older people.
The report, published by the Committee on the Medical Effects of Air Pollutants (COMEAP), adds significant weight to previous studies that linked cognitive decline and dementia to 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.
The committee said that it couldn’t put a number on how many older people had seen a mental decline linked to air pollution, largely due to a scarcity of investigative studies that might provide causal evidence.
The report identifies three main mechanisms for how air pollution could be accelerating mental declines. Chief among these is the damage done to blood vessels by tiny particulate matter, which can affect blood supply to the brain: Dementia can result from a reduction in blood supply to brain cells. There are a number of human, as well as animal, studies showing the effect pollution can have on blood vessels.
“Thanks to an immense amount of work in the last several years, we can say with confidence this link exists,” said Brian Castellani from Durham University. “It shows exposure to dirty air in early life can have significant later-life impacts on brain health.”
Stefan Reis, from the UK Centre for Ecology and Hydrology, said: “The findings of COMEAP are not surprising, but add further weight to the understanding that air pollutions health impacts are much wider and likely more profoundly affecting public health beyond the traditionally known immediate effects.”
Recommendations have been made for further research which COMEAP believes would help develop the evidence on this important topic.