A new preclinical study has found exposure to nanoplastics (tiny plastic particles) can rapidly progress Alzheimer's disease and, subsequently, spread from the brain to other key organs such as the liver, heart and gut.
The study, co-led by Monash University and South China University of Technology, investigated how environmental-level polystyrene nanoplastic exposure influences the progression of Alzheimer's disease from the brain to other parts of the body. Studies in mice revealed that nanoplastic-induced neurological damage is not confined within the brain, but expands systemically through the 'gut–liver–brain axis'.
In mice exposed to polystyrene nanoplastics, Alzheimer's-like symptoms were shown to stimulate 'microglia' immune cell activation in the brain, leading to neuroinflammation and neurodegeneration. This in turn led to peripheral health implications beyond the brain, including fatty liver disease, abnormal build-up of fat and gut microbiota imbalance.
Humans are involuntarily exposed to plastics through inhalation, dermal contact and the consumption of contaminated food and water, and plastic particles have been detected in human lungs, bloodstream and, very recently, in the human brain.
This, however, is the first study to show how rapidly nanoplastics can evolve from the brain to other parts of the body.
Lead author of the Environment and Health study Professor Pu Chun Ke, an Adjunct Professor with the Monash Institute of Pharmaceutical Sciences, said the findings further support mounting evidence that nanoplastics are a hidden threat to our health.
"These findings, although still early stage, suggest that nanoplastic-induced neurological damage is not confined within the brain but expands systemically through the communication network connecting the gastrointestinal tract, liver, and central nervous system, otherwise known as the gut-liver-brain axis," Professor Ke said.
"As a result, nanoplastics set off a chain reaction whereby Alzheimer's disease develops and spreads from the top down."
Professor Ke, who has been spearheading research into plastic-induced health implications for nearly two decades, said these findings highlight the urgent need to better understand the interplay between the local neurological and systemic effects of an environmental-level nanoplastic exposure, along with their broader, yet unknown, implications for human health.
"Furthermore, while the current study was focused on polystyrene nanoplastics, future studies should investigate whether different nanoplastic variants elicit similar or distinct neurotoxic effects, to support comprehensive risk assessment and the development of preventive strategies for environmentally induced neurological disorders," Professor Ke concluded.
Professor Ke and his team first reported how nanoplastics impair algal photosynthesis back in 2010. Since then, he has gone on to lead research into the role of nanoplastics in promoting the onset and progression of other diseases, including Parkinson's and vascular damage.
The full study titled Cerebral to Systemic Representations of Alzheimer's Pathogenesis Stimulated by Polystyrene Nanoplastics can be found here.
DOI: https://doi.org/10.1021/envhealth.5c00160
