New research suggests that magnetite, a particulate in air pollution, can induce signs and symptoms of Alzheimer's disease. Alzheimer's disease is a type of dementia that causes memory loss, cognitive decline, and significantly reduced quality of life. It affects millions of people worldwide and is the leading cause of death among older people.
The study, led by Associate Professor Cindy Gunawan and Associate Professor Kristine McGrath of the University of Technology Sydney (UTS), was recently published in the journal Environment International.
A team of researchers from the University of Technology Sydney, the University of New South Wales Sydney and Singapore's Agency for Science, Technology and Research studied the effects of air pollution on mouse brain health as well as human neuronal cells in the lab.
Their aim is to better understand how exposure to toxic air pollution particles causes Alzheimer's.
Associate Professor Gunawan of the Australian Institute of Microbiology and Infection (AIMI) said: "Less than 1% of Alzheimer's cases are hereditary, so it is likely that environment and lifestyle play a key role in the development of the disease. Previous studies have shown that people living in areas with high levels of air pollution are at greater risk of developing Alzheimer's disease. Magnetite is a magnetic iron oxide compound, and more magnetite is also found in the brains of people with Alzheimer's. However, this is the first time to study whether the presence of magnetite particles in the brain actually causes signs of Alzheimer's. "
The researchers exposed healthy mice and mice genetically predisposed to Alzheimer's disease to very fine particles of iron, magnetite and diesel hydrocarbons for four months. They found that the pathological changes in magnetite-induced Alzheimer's disease were most consistent.
This includes the loss of nerve cells in the hippocampus (an area of the brain that is essential for memory) and the somatosensory cortex (an area that processes sensations in the body). The formation of amyloid plaques was increased in mice that already had a predisposition to Alzheimer's.
The researchers also observed behavioral changes in mice consistent with Alzheimer's, including increased stress and anxiety and impaired short-term memory, especially in genetically susceptible mice.
"Magnetite is a fairly common air pollutant. It comes from high-temperature combustion processes such as vehicle exhaust, wood burning, and coal-fired power stations, as well as brake pad friction and engine wear," said Associate Professor McGrath in the UTS School of Life Sciences. "When we inhale air pollutants, these magnetite particles pass through the lining of the nasal cavity, bypassing the blood-brain barrier and entering the brain from the small structure at the base of the brain responsible for processing odors, the olfactory bulb. "
Researchers have found that magnetite induces an immune response in mouse and human neuronal cells in the lab. It triggers inflammation and oxidative stress, which in turn leads to cell damage. Inflammation and oxidative stress are known to be important factors in the development of dementia.
Dr. Charlotte Fleming, co-first author of the UTS School of Life Sciences, said: "Magnetite-induced neurodegeneration is also independent of disease states, and signs of Alzheimer's can also be seen in the brains of healthy mice. "
These results will be of interest to health workers and policymakers. It recommends that people take steps to minimize their exposure to air pollution and consider ways to improve air quality and reduce the risk of neurodegenerative diseases.
This research has important implications for air pollution guidelines. Magnetite particles should be included in the recommended safety thresholds for the AQI, while more needs to be done to reduce emissions from cars and coal-fired power stations.
编译来源：ScitechDaily