New study finds entire spoonful of microplastics in people’s brains — and 3 times as much in those with dementia

Your brain is 99.5% brain tissue — but the rest? Plastic. 

That’s the unsettling takeaway from a new study co-lead by Matthew Campen, who found microplastics in human brains at far higher levels than other organs. Even more troubling, these tiny particles are accumulating rapidly, having increased 50% over the past eight years.

“There’s much more plastic in our brains than I ever would have imagined or been comfortable with,” said Campen, distinguished professor of pharmaceutical sciences at the University of New Mexico in Albuquerque.

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On average, the brain samples studied contained about 7 grams of microplastics — roughly the weight of an average plastic spoon. 

To make matters worse, the study also found up to 10 times the amount of microplastics in the brains of 12 dementia patients compared to healthy brains. While the correlation is clear, researchers cautioned that further study is needed to establish a direct link.

The research team analyzed 52 brain samples — 28 from autopsies conducted in 2016 and 24 from 2024. While microplastics were present in every single sample, the concentrations were notably higher in the more recent specimens.

Additional brain samples dating back to 1997 followed the same alarming pattern, with higher microplastic levels found in newer samples.

Campen said the increase mirrors the global surge in plastic waste. Global plastic production has more than doubled over the past two decades, now totaling about 400 million tons annually.

Scientists previously found that humans consume 5 grams of microplastics each week, which is about the weight of a credit card. Microplastics have been detected in various parts of the body, including the lungs, liver, kidneys, placenta, blood, semen and even breast milk.

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The most common microplastic that researchers from the University of New Mexico detected was polyethylene, widely used in packaging materials like bottles and cups. What’s more, many of these particles were smaller than previously thought — some are no bigger than viruses. 

Campen said these tiny fragments are small enough to cross the blood-brain barrier, though he noted that the exact process of how they are transported to the brain remains unclear. He suspects that a primary route of entry is through our food, particularly meat. 

“The way we irrigate fields with plastic-contaminated water, we postulate that the plastics build up there,” Campen said. “We feed those crops to our livestock. We take the manure and put it back on the field, so there may be a sort of feed-forward biomagnification.” 

Other studies suggest another potential route for microplastics to enter the human body: through the nose. The olfactory bulb might allow these tiny particles to travel directly to the brain when we breathe.

Despite a global push to reduce plastic production, researchers warn that the microplastic threat isn’t going anywhere anytime soon. Plastic takes decades to break down into microscopic particles, meaning the environmental contamination will continue to grow for years to come.

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While the full health impact of microplastics remains uncertain, studies suggest they can damage cells, trigger inflammation, disrupt organ function and alter immune responses. Exposure to these tiny particles has also been linked to an some cancers. 

Though microplastics may be nearly impossible to avoid entirely, there are steps you can take to limit your exposure.

Start by cutting out single-use plastics — think food and beverage packaging, as well as takeout containers. Swap plastic storage containers for glass or metal, and never reheat food in plastic containers in the microwave.

Experts also recommend filtering your tap water, investing in high-quality air filters for your home and cleaning your living space more frequently.

Another simple but effective tip: cut back on processed foods, which tend to have higher levels of these tiny particles.