However, the research is still a long way from proving that the air pollution particles cause or exacerbate Alzheimer’s.
Scientists at Lancaster University examined brain tissue from 37 people in Manchester, UK and Mexico City, aged between 3 and 92 and found it contained an abundance of magnetite particles, an iron oxide. Magnetite particles are known to form biologically in human brains, but they are typically small and crystal-shaped, in contrast to the larger, round particles that were observed in the study. So, given their different qualities, researchers connected them with air pollution. “Many of the magnetite particles we found in the brain are rounded nanospheres, because they were formed as molten droplets of material from combustion sources, such as car exhausts, industrial processes and power stations, anywhere you are burning fuel”, said Prof. Barbara Maher who led the research. The claim that these particles come from air pollution becomes stronger, as scientists also traced particles of metals such as platinum that are very rarely found naturally in the body, but are found in many car engines. “We also observed other metal-bearing particles in the brain, such as platinum, cobalt and nickel. Things like platinum are very unlikely to come from a source within the brain. It is a bit of an indicator of a [vehicle] catalytic converter source”, she said. Their work was published in the Proceedings of the National Academy of Sciences.
Because of the small size of the magnetite pollution particles (less than 200nm in diameter), they can enter the brain directly through the olfactory nerve and by crossing the damaged olfactory unit. Abnormal accumulation of brain metals seems to play a key role in Alzheimer’s disease and magnetite was directly associated with the damage seen in the brain of people with Alzheimer, according to a recent study. Only in this case, the abnormal accumulation means that the round particles outnumbered the crystal shaped ones by about 100 to one! ‘Oxidative cell damage is one of the hallmark features of Alzheimer’s disease, and this is why the presence of magnetite is so potentially significant, because it is so bioreactive’, said Maher. ‘We have not demonstrated a causal link between these particles and Alzheimer’s disease but when you consider that magnetite has been found in higher concentrations in Alzheimer’s brains and you know that magnetite is pernicious in its effect on the brain, then having a direct [air pollution] source of magnetite right up your olfactory bulb and into your frontal cortex is not a great idea’, she said.
Source: The guardian