Air pollution is touted as a possible cause of dementia and general cognitive decline in older adults, according to major new research conducted on behalf of the UK government and released on Monday.

The Committee on the Medical Effects of Air Pollutants (COMEAP) reached its conclusion after examining nearly 70 human studies that were looking for links between air pollution and reduced mental abilities.

“Air pollution is likely to contribute to the decline in mental capacity and dementia in the elderly,” the report says.

The researchers believe the most likely way for this to happen is through the circulatory system. “It is known that air pollutants, especially small particles, can affect the heart and blood vessels, including the brain,” the study says.

The report says the evidence linking exposure to air pollutants to effects on the brain has become stronger “over the past 15-20 years”. Among the possible mechanisms for a negative effect on brain activity is the “transmission of small molecules from the lung into the bloodstream and thus into the brain”.

The researchers said air pollution may also stimulate immune cells in the brain that may damage neurons, although it is unclear if it is a significant factor in current pollution levels in the UK.

Meanwhile, while the research has found a link between dementia and air pollution, its authors say they don’t have enough data to determine how many cases of dementia are attributable to this cause.

The report also says that “there is evidence that air pollution increases the risk of cardiovascular disease, including cerebrovascular disease,” which are known to have a negative impact on mental abilities.

In light of these findings, COMEAP recommended further research to delve into this issue.

According to the UK’s National Health Service (NHS), more than 850,000 people in Britain suffer from dementia, with the elderly being the most vulnerable population group. It is believed that one in 14 people over the age of 65 has dementia, and the condition affects one in six people over the age of 80.