Microplastics in human brain: Silent threat leading to dementia

A recent study by biochemist and environmental scientist Matthew Campen and his team at the University of New Mexico has uncovered concerning evidence of microplastics and nanoplastics (MNPs) accumulating in human organs, particularly the brain.

As these particles continue to pervade the environment—from the air we breathe to the food we consume—the full extent of their impact on human health remains unclear, the study published by Nature Medicine notes.

While research in cell cultures and animals suggests potential harm, the complexities of human health risks are still being explored.

Campen’s study specifically investigates the accumulation of inhaled MNPs in human organs such as the brain, liver, and kidneys. Their research, which analyzed tissue samples from autopsies conducted in 2016 and 2024, found that MNPs were most concentrated in the brain, surpassing concentrations in the liver or kidneys. Most notably, the accumulation was even more pronounced in individuals who had dementia. Additionally, plastic levels were found to be significantly higher in 2024 compared to 2016, signalling a concerning increase in environmental plastic exposure over time.

In order to accurately assess microplastic buildup in human organs, Campen and his team employed a more advanced technique — pyrolysis gas chromatography-mass spectrometry — over traditional microscopic methods. This allowed them to detect even the tiniest nanoplastics, which often evade detection by conventional tools but are capable of crossing the blood-brain barrier. The study’s findings were both surprising and concerning: while the liver and kidneys had similar levels of MNPs, the brain tissue showed the highest concentrations. Furthermore, the levels of microplastics in brain and liver samples from 2024 were much higher than in samples from 2016, with the year of death being the key variable influencing these concentrations.

The researchers also expanded their study by examining older brain tissue samples from 1997 to 2013, discovering higher plastic concentrations in the more recent samples. When they compared individuals with and without documented dementia, they found that those with the condition had notably higher plastic accumulation in their brains. The most common types of plastics found were polyethene, polypropylene, polyvinyl chloride, and styrene-butadiene rubber.

Using advanced microscopy techniques, the team observed aged, shard-like plastic fragments embedded in the tissues. In the liver and kidney, these fragments ranged from one to five micrometres in size, but the brain samples contained even smaller particles, often less than one micrometre. In dementia cases, the plastic particles appeared to cluster inside inflammatory cells and along blood vessel walls.

The study’s findings suggest that environmental MNP levels are rising, and these particles are likely to enter human organs in increasing quantities. While this research reveals a link between plastic accumulation and specific health conditions, further studies involving more diverse populations and longer-term observations are essential to fully understand the health implications of MNP exposure. The rising presence of microplastics in human tissue underscores the need for urgent action to assess exposure routes and potential health risks, particularly to the brain.

By Tamilla Hasanova