Lancaster researchers discover potential link between air pollution and Alzheimer's

Tiny magnetic particles from air pollution have for the first time been discovered to be lodged in human brains – and researchers think they could be a possible cause of the degenerative condition.

Researchers at Lancaster University found abundant magnetite nanoparticles in the brain tissue from 37 people aged three to 92-years-old who lived in Manchester and Mexico City.

Prof Barbara Maher, from Lancaster Environment Centre, and colleagues from Oxford, Glasgow, Manchester and Mexico City used analysis to identify the particles as magnetite.

She said: “The particles we found are strikingly similar to the magnetite nanospheres that are abundant in the airborne pollution found in urban settings, especially next to busy roads, and which are formed by combustion or frictional heating from vehicle engines or brakes.

“Our results indicate that magnetite nanoparticles in the atmosphere can enter the human brain, where they might pose a risk to human health, including conditions such as Alzheimer’s disease.”

Leading Alzheimer’s researcher Prof David Allsop, of Lancaster University’s Faculty of Health and Medicine, said: “This finding opens up a whole new avenue for research into a possible environmental risk factor for a range of different brain diseases.”

This strongly magnetic mineral is toxic and has been implicated in the production of reactive oxygen species (free radicals) in the human brain, which are associated with neurodegenerative diseases including Alzheimer’s disease.

Unlike angular magnetite particles that are believed to form naturally within the brain, most of the observed particles were spherical, with diameters up to 150 nm, some with fused surfaces, all characteristic of high-temperature formation – such as from vehicle (particularly diesel) engines or open fires.

The spherical particles are often accompanied by nanoparticles containing other metals, such as platinum, nickel, and cobalt.

Other sources of magnetite nanoparticles include open fires and poorly sealed stoves within homes.

Particles smaller than 200 nm are small enough to enter the brain directly through the olfactory nerve after breathing air pollution through the nose.

The results have been published in the paper ‘Magnetite pollution nanoparticles in the human brain’ by the Proceedings of the National Academy of Sciences.

The paper’s authors are Barbara Maher, David Allsop, Vassil Karloukovski and Penny Foulds from Lancaster University; Imad Ahmed from the University of Oxford; Donald MacLaren from the University of Glasgow; David Mann from the University of Manchester; Ricardo Torres-Jardon from the Universidad Nacional Autonoma de Mexico; and Lilian Calderon-Garciduenas from The University of Montana.