Magnetic particles in air pollution linked to Alzheimer’s

Researchers at the University of Technology  in Sydney have found that magnetite, a tiny particle found in air pollution, can induce signs and symptoms of Alzheimer’s disease.

The study, titles ‘Neurodegenerative effects of air pollutant particles: Biological mechanisms implicated for early-onset Alzheimer’s disease’ has been published in Environment International.

In order to to better understand how exposure to toxic air pollution particles could lead to Alzheimer’s disease the team looked at the impact of air pollution on the brain health of mice and human neuronal cells in the lab.

Associate Professor Gunawan, from the Australian Institute for Microbiology and Infection said: ‘Fewer than 1% of Alzheimer’s cases are inherited, so it is likely that the environment and lifestyle play a key role in the development of the disease.

‘Previous studies have indicated that people who live in areas with high levels of air pollution are at greater risk of developing Alzheimer’s disease. Magnetite, a magnetic iron oxide compound, has also been found in greater amounts in the brains of people with Alzheimer’s disease.

‘However, this is the first study to look at whether the presence of magnetite particles in the brain can indeed lead to signs of Alzheimer’s.’

The researchers exposed healthy mice and those genetically predisposed to Alzheimer’s to fine particles of iron, magnetite, and diesel hydrocarbons over four months. Magnetite was found to induce the most consistent Alzheimer’s disease symptoms, including the loss of neuronal cells in an area of the brain crucial for memory, and also in an area that processes sensations from the body. 

Magnetite is an oxide of iron and is the most magnetic of all the naturally occurring minerals on earth. 

The researchers also observed behavioural changes in  in the mice that were consistent with Alzheimer’s disease including increased stress and anxiety and short-term memory impairment, the latter particularly in the genetically predisposed mice.

Associate Professor McGrath from the UTS School of Life Sciences said: ‘Magnetite is a quite common air pollutant. It comes from high-temperature combustion processes like vehicle exhaust, wood fires and coal-fired power stations as well as from brake pad friction and engine wear.

‘When we inhale air pollutant, these particles of magnetite can enter the brain via the lining of the nasal passage, and from the olfactory bulb, a small structure on the bottom of the brain responsible for processing smells, bypassing the blood-brain barrier.’

The researchers found that magnetite induced an immune response in the mice and in the human neuronal cells in the lab. It triggered inflammation and oxidative stress, which in turn led to cell damage. Inflammation and oxidative stress are significant factors known to contribute to dementia.

The results will be of interest to health practitioners and policymakers. It suggests that people should take steps to reduce their exposure to air pollution as much as possible, and consider methods to improve air quality and reduce the risk of neurodegenerative disease.

The researchers believe their study has implications for air pollution guidelines, suggesting that magnetite particles should be included in the recommended safety threshold for air quality index.

The full research paper can be read here.