Alarming levels of microplastics discovered in human brain tissue, linked to dementia: Study

In a comprehensive Commentary published today in Brain Medicine , researchers discuss alarming new evidence about microplastic accumulation in human brain tissue, providing critical insights into potential health implications and prevention strategies. This Commentary examines findings from a groundbreaking Nature Medicine article by Nihart et al. (2025) on bioaccumulation of microplastics in decedent human brains.

The research reveals that human brains contain approximately a spoon's worth of microplastics and nanoplastics (MNPs), with levels 3-5 times higher in individuals with documented dementia diagnoses. More concerning still, brain tissues showed 7-30 times higher concentrations of MNPs compared to other organs like the liver or kidney.

"The dramatic increase in brain microplastic concentrations over just eight years, from 2016 to 2024, is particularly alarming," notes Dr. Nicholas Fabiano from the University of Ottawa's Department of Psychiatry, lead author of the Commentary. "This rise mirrors the exponential increase we're seeing in environmental microplastic levels."

Of particular concern are particles smaller than 200 nanometers, predominantly composed of polyethylene, which show notable deposition in cerebrovascular walls and immune cells. This size allows them to potentially cross the blood-brain barrier, raising questions about their role in neurological conditions.

The Commentary review highlights practical strategies for reducing exposure, noting that switching from bottled to filtered tap water alone could reduce microplastic intake from 90,000 to 4,000 particles per year. "Bottled water alone can expose people to nearly as many microplastic particles annually as all ingested and inhaled sources combined," says Dr. Brandon Luu, an Internal Medicine Resident at the University of Toronto. "Switching to tap water could reduce this exposure by almost 90%, making it one of the simplest ways to cut down on microplastic intake." Other significant sources include plastic tea bags, which can release millions of micro and nano-sized particles per brewing session. He also highlights that how we heat and store food matters. "Heating food in plastic containers-especially in the microwave-can release substantial amounts of microplastics and nanoplastics," he explains. "Avoiding plastic food storage and using glass or stainless steel alternatives is a small but meaningful step in limiting exposure. While these changes make sense, we still need research to confirm whether lowering intake leads to reduced accumulation in human tissues."

The research team also explores potential elimination pathways, including evidence that sweating might help remove certain plastic-derived compounds from the body. However, Dr. David Puder, host of the Psychiatry & Psychotherapy Podcast, warns, "We need more research to wrap our heads around microplastics-rather than wrapping our brains in them-since this could be one of the biggest environmental storms most people never saw coming."The commentary calls for urgent research priorities, including establishing clear exposure limits and assessing long-term health consequences of microplastic accumulation. The authors emphasize the need for large-scale human studies to determine dose-response relationships between microplastic exposure and chronic health outcomes.

Reference:

Human microplastic removal: what does the evidence tell us?, Brain Medicine, DOI:10.61373/bm025c.0020.