AIR pollution is fuelling a rise in dementia, the UK Government has acknowledged for the first time.
Toxic airborne particles from cars and fossil fuels have long been associated with rapidly increasing rates of the disease in the UK and the developed world.
Now, a major independent review has confirmed the link after analysing dozens of human studies.
The researchers concluded it was ‘likely that air pollution can contribute to a decline in mental ability and dementia in older people’.
They believe the primary way this happens is by tiny toxic particles seeping into the bloodstream after being breathed into the lungs.
The pollutants then irritate blood vessels and disrupt circulation to the brain. Over time, this can lead to vascular dementia.
It is also likely that in rare cases very small air pollution particles can pass the blood-brain barrier and damage neurons directly.
But this does not seem to be an important mechanism at the level of air pollution currently in the UK, the report found.
While a link has been established, there is not enough evidence yet to say how many dementia cases are the result of air pollution.
Some studies have suggested up to a fifth of patients with the disease are linked to exposure to toxic pollutants.
The 290-page report was carried out by the Committee on the Medical Effects of Air Pollutants (COMEAP), led by Imperial College London’s Professor Frank Kelly.
Researchers looked at 70 human studies, which included population-based research, taken from the general public, and experiments in a laboratory.
They concluded: ‘We think there is a strong case for the effects of air pollutants on the cardiovascular system having a secondary effect on the brain.
‘…we think it likely that such effects have an effect on the blood supply to the brain. That such an effect might well lead to damage to the brain seems, to us, likely.
‘We therefore regard the association between exposure to air pollutants and effects on cognitive decline and dementia as likely to be causal with respect to this mechanism.’
