New research has shed light on the relationship between industrial air pollution and nanomagnetic particles in the brain. For almost 30 years, it was thought that magnetic particles occur naturally in the brain as a result of the use of iron in normal brain functions. This line of thinking was supported by the findings of geophysicist Joe Kirschvink at California Institute of Technology, which determined the presence of naturally occurring magnetic particles in brains, 25 years ago.
The nature of these magnetic particles is important to determine, since high concentrations of the particle magnetite are also found in the brains of Alzheimer’s patients. Although it was thought to be naturally occurring, magnetite is indeed toxic. It can cause oxidative stress, which disrupts cellular function and creates harmful free radicals. Prior research has shown a connection between high concentrations of magnetite and Alzheimer’s, and a study from 2015 suggests that it can increase the toxicity of β amyloid plaques, which are protein clumps which interfere with cell signaling. This suggests that magnetite may play a prominent role in Alzheimer’s.
While this link is not yet conclusive between magnetite and Alzheimer’s, the cellular damage caused by magnetite are consistent with the damage seen in Alzheimer patients.
Physicist Barbara Maher, co-director of the Centre for Environmental Magnetism and Paleomagnetism at Lancaster University sought out to determine whether all of the magnetite found in human brains originated from biological processes. “The paradigm until now has been that magnetite just forms naturally in the brain, given how prolific magnetite particles are in the atmosphere, I wondered if they had gained entry into the human brain” says Maher.
Maher’s research used high-resolution imaging to examine postmortem samples of brain matter taken from 37 human brains, from people who had lived in Mexico City and Manchester, UK. The researchers found biological magnetite, but for every one of those particles, they found at least 100 particles of magnetite that seemed to be derived from pollution. Researchers were able to establish this noting that the nanosphere shaped particles had properties which suggested they were formed in temperatures much higher than those found in the human body. The particles were 150 nanometers or less in diameter, which is small enough to have been inhaled and to have entered the brain through the olfactory bulb. Though further research is needed, the study suggests the possibility of a relationship between environmental factors and Alzheimer’s.
Maher notes that air quality studies in both Mexico City and the UK have shown urban areas to have high quantities of airborne magnetite particles, particularly along roadsides.