New research has found alarmingly high levels of microplastics in the human brain that could potentially be linked to the global rise in Alzheimer's disease. 

The study, led by researchers from the University of New Mexico, has been published as a pre-print online, which means it has yet to be reviewed by other scientists.

But the findings are already causing alarm because the highest concentrations of microplastics were found in 12 brain samples taken from people that died with dementia, including Alzheimer's disease, suggesting there might be a link.

Humans are exposed to microplastics - fragments of plastic smaller than five millimeters in length - all the time. 

They're in our air, water, food, cosmetics and practically everywhere else. They also work their way into our organs when we breathe or ingest them.

The researchers measured microplastic concentrations in 51 liver, kidney, and brain samples collected in 2016 and 2024.

All of the samples contained the particles, but the brain samples contained seven to 30 times more than liver or kidney samples.

What's more, 12 brain samples from people that died with dementia and or Alzheimer's contained up to 10 times more plastic by weight than healthy samples, the New Lede reported. 

These early findings do not prove that there is a link between microplastics in the brain and incidence of dementia or Alzheimer's. 

But they do suggest a need for further research, as cases of these diseases are rising across the globe and the amount of plastic in brains has increased over 50 percent in the past eight years, the researchers wrote in their report.

Additionally, previous studies in mice have linked nanoplastics (plastic particles that even smaller than microplastics) in the brain to cognitive changes, Parkinson's disease and some types of dementia. 

One such study, published in the journal Science Advances in 2023, found that nanoplastics can interact with a protein called alpha-synuclein. 

This protein is found in every brain and plays a roll in nerve cell communication.

Plastic particles can bind tightly to alpha-synuclein and cause it to form toxic clumps similar to what is seen in Parkinson's disease and associated types of dementia.

In the pre-print study, the researchers site this mechanism as a potential driver of human brain disease that warrants future investigation.

In recent years, a wave of research has found microplastics in almost every part of the human body, including in the heart, testicles, breast milk, placenta, liver, kidneys, and brain. 

But this new study suggests that the brain accumulates unusually high concentrations of microplastics, and that those concentrations are rising over time.

'It's pretty alarming,' Matthew Campen, toxicologist at the University of New Mexico and lead author of the study, told the New Lede. 

'There's much more plastic in our brains than I ever would have imagined or been comfortable with.' 

Scientists still don't fully understand how microplastics impact human health. 

But another recent study suggests that microplastics in the arteries may increase risk of heart attack and other cardiovascular problems.

And chemicals often found in plastics have been linked to a variety of health problems, including cancers, metabolic disorders, attention deficit/hyperactivity disorder and fertility issues.

Rising amounts of microplastics in the brain could theoretically be influencing global trends in neurological disease, like Alzheimer's - a form of dementia.

Global dementia cases are on track to triple by 2050, according to a 2022 study published in the Lancet Public Health. 

But more research is needed in order to link microplastics to this trend. 

There are numerous risk factors for dementia and Alzheimer's, including age, genetics, head injury, hearing loss and more. 

But currently, there is no evidence to suggest that microplastic accumulation in the brain is one of these risk factors. 

This study provides a new incentive for research on how microplastics impact human brain health, as it could be important to understanding the global rise in dementia and Alzheimer's cases.