Magnetite from air pollution found in brain tissue for the first time, research finds

Research published today (Monday 05 September) in PNAS has found magnetite, a magnetic form of iron oxide, from air pollution in human brain tissue for the first time.

A small number of the brains in this study were from people who died with Alzheimer’s disease, leading the researchers to suggest that magnetite from air pollution could contribute to the disease process.

Researchers at Lancaster University used a series of techniques to examine tiny particles of magnetite in the brain tissue of 29 people who lived in Mexico City, Mexico (aged 3 to 85 years) and 8 people from Manchester, UK (aged 62 to 92 years). Magnetometry was used to find out how much magnetic material was in each sample of brain tissue. For a subset of the samples, the tissue was degraded and the magnetite particles extracted to be viewed with electron microscopy.The magnetite particles they observed have the same shape and surface texture as particles formed at high temperatures, such as in car engines, and present in air pollution. Magnetite has been observed in the brains of people with Alzheimer’s disease in earlier studies, but this is the first time magnetite particles coming from air pollution have been described in the brain.

Dr Clare Walton, Research Manager at Alzheimer’s Society, said:

'Magnetite, a form of iron oxide, has previously been seen in amyloid plaques in the brains of people who have died with Alzheimer’s disease. This magnetite is generally thought to come from iron found naturally in the brain and there is no strong evidence to suggest that it causes Alzheimer’s disease or makes it worse.

'This study offers convincing evidence that magnetite from air pollution can get into the brain, but it doesn’t tell us what effect this has on brain health or conditions such as Alzheimer’s disease.  

'The causes of dementia are complex and so far there hasn’t been enough research to say whether living in cities and polluted areas raises the risk of dementia. Further work in this area is important, but until we have more information people should not be unduly worried. There are more practical ways to lower your chances of developing dementia such as regular exercise, eating a healthy diet and avoiding smoking.'