Study shows microplastics can alter behaviour, brain

NEW YORK: The infiltration of microplastics is as widespread in the body as it is in the environment, leading to changes in behaviour and also in the brain, especially in the elderly people, according to a study.

Plastics -- in particular, microplastics -- are among the most pervasive pollutants on the planet, finding their way into the air, water systems and food chains around the world.

Researchers from the University of Rhode Island in the US focused on neurobehavioural effects and inflammatory response to exposure to microplastics, as well as the accumulation of microplastics in tissues, including the brain.

The team exposed young and old mice to varying levels of microplastics in drinking water over the course of three weeks.

The findings, published in the International Journal of Molecular Science, showed that microplastic exposure induces both behavioural changes and alterations in immune markers in liver and brain tissues.

The study mice began to move and behave peculiarly, exhibiting behaviours akin to dementia in humans. The results were even more profound in older animals.

"To us, this was striking. These were not high doses of microplastics, but in only a short period of time, we saw these changes," said Jaime Ross, an assistant professor of biomedical and pharmaceutical sciences at the Ryan Institute for Neuroscience and the College of Pharmacy, at the University of Rhode Island in the US.

"Nobody really understands the life cycle of these microplastics in the body, so part of what we want to address is the question of what happens as you get older. Are you more susceptible to systemic inflammation from these microplastics as you age? Can your body get rid of them as easily? Do your cells respond differently to these toxins?"

Further, the researchers found that the particles had begun to bioaccumulate in every organ, including the brain, as well as in bodily waste.

"Given that in this study the microplastics were delivered orally via drinking water, detection in tissues such as the gastrointestinal tract, which is a major part of the digestive system, or in the liver and kidneys was always probable," Ross said.

"The detection of microplastics in tissues such as the heart and lungs, however, suggests that the microplastics are going beyond the digestive system and likely undergoing systemic circulation. The brain blood barrier is supposed to be very difficult to permeate. It is a protective mechanism

against viruses and bacteria, yet these particles were able to get in there. It was actually deep in the brain tissue."

That brain infiltration also may cause a decrease in glial fibrillary acidic protein (called "GFAP"), a protein that supports many cell processes in the brain, results have shown.

"A decrease in GFAP has been associated with early stages of some neurodegenerative diseases, including mouse models of Alzheimer's disease, as well as depression," Ross said. "We were very surprised to see that the microplastics could induce altered GFAP signalling."

"We want to understand how plastics may change the ability for the brain to maintain its homeostasis or how exposure may lead to neurological disorders and diseases, such as Alzheimer's disease," she said.