Microplastics May Block Blood Flow in the Brain

Microplastics in the bloodstream may cause blockages the brain and affect our brain functioning and behavior, according to recent research.

Environmental biologists tested the effects of microplastics on the brains of young male mice, taking pictures of the blood vessels in their brains and observing their behavior.

They found a new way in which microplastics may disrupt blood vessels and brain health, without crossing from the bloodstream to the brain.

Microplastics are tiny particles of plastic, that break off larger pieces, as plastic items degrade.

Widely recognized as significant environmental pollutants, they have increasingly been investigated as a potential health risk.

Microplastics can enter our bodies if we breathe them in, eat them or otherwise come into contact with them. Once in our bodies, some microplastics may enter our bloodstream and then travel around to different organs.

Previous studies have shown they may interact with our hormones, or enter our cells and disrupt our DNA, potentially increasing the risk of certain cancers—especially when they’re very tiny pieces of plastic, called nanoplastics.

These nanoplastics have been linked to brain disorders and inflammation, as well as cancer risk, but scientists are still trying to work out what microplastics—slightly larger, but still tiny, pieces of plastic—might do.

In this study, scientists injected plastics of three different sizes—micro, smaller micro and nano—into eight-week-old male mice, at levels designed to mimic amounts to which humans might be exposed.

These plastics were fluorescent in color, used as a labeling system so scientists could keep track of where they went inside the mice and what happened as a result.

Using very advanced techniques, the scientists took images of the blood vessels inside the mice’s brains to track the plastics.

Later, they also took blood samples from the mice to understand how the microplastics had interacted with cells in the bloodstream.

And they conducted behavioral experiments to test whether the plastics had impacted the mice’s memory, movement, exploratory behavior and endurance.

The scientists found that the microplastics were ingested by immune cells—cells that fight against infections and invaders—which changed the size and shape of these immune cells and caused them to get blocked in small blood vessels.

This was especially true for larger pieces of microplastics that got stuck in very narrow blood vessels, called capillaries, which could cause prolonged obstructions to blood flow in the brain.

Just 30 minutes after being injected with microplastics, blood flow could be obstructed in the mice’s brains.

There were behavioral changes too. The scientists observed that the mice showed signs of worse memory, movement, speed, motor skills and endurance after being injected with the microplastics.

Most of these issues got better four weeks after the experiment, but some blood vessel blockages remained.

This could raise alarm bells for the potential effect of microplastics on human brain health, for instance increasing the risk of stroke or cognitive decline—however, more research is needed before coming to those conclusions.

The size and structure of blood vessels in the brains of mice are different to those of humans, so it is not certain that the microplastics have the same effect in us.

The scientists recommended that further research be undertaken on the long-term health risks posed by microplastics, particularly among people with conditions that affect their heart and blood vessels, such as heart disease.

This study was published in scientific journal Science Advances on January 22.

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Reference

Huang, H., Hou, J., Li, M., Wei, F., Liao, Y., Xi, B. (2025). Microplastics in the bloodstream can induce cerebral thrombosis by causing cell obstruction and lead to neurobehavioral abnormalities, Science Advances, 11(4). https://doi.org/10.1126/sciadv.adr8243