A new international scientific study has raised serious concerns about the impact of microplastics on human brain health, revealing that these tiny plastic particles can trigger inflammation and may accelerate the progression of neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease.

Conducted by researchers from University of Technology Sydney and Auburn University in the United States, the study found that humans are estimated to ingest around 250 grams of microplastics annually — an amount roughly equivalent to the size of a dinner plate. The findings were published in the peer-reviewed journal Molecular and Cellular Biochemistry.

The research identified multiple biological pathways through which microplastics can disrupt brain function. One of the most alarming mechanisms is the weakening of the blood–brain barrier — a critical protective layer that normally prevents harmful substances from entering brain tissue. When this barrier becomes permeable, inflammatory molecules and immune cells can infiltrate brain tissue, increasing the risk of chronic inflammation and long-term damage.

Microplastics were also found to overstimulate immune cells within the brain. When the body identifies these particles as foreign substances, it activates microglia, the brain’s primary immune cells. This sustained immune response, while intended to protect the brain, can instead contribute to prolonged inflammation and cellular damage if constantly triggered by persistent microplastic exposure.

Another major risk highlighted by the study is oxidative stress. Microplastics increase the production of reactive oxygen species, unstable molecules that damage cells, proteins and DNA. When the brain’s natural antioxidant defences are overwhelmed, this can lead to tissue degeneration and loss of healthy brain function over time.

The research further demonstrated that microplastics interfere with mitochondrial activity — the process by which cells generate energy. Mitochondria are responsible for producing adenosine triphosphate (ATP), the essential fuel for cell survival and activity. When this energy supply is disrupted, neurons struggle to function effectively. Persistent energy deficits can weaken brain signalling and contribute to progressive neurodegeneration.

Damage to neurons was found to be a downstream consequence of these processes. As inflammation increases and cellular energy production declines, neurons become more vulnerable to injury and loss. This combination of immune activation, oxidative stress and mitochondrial dysfunction creates a cascade of damage that slowly deteriorates brain tissue over time.

The study also examined how microplastics could worsen hallmark features associated with Alzheimer’s and Parkinson’s. It found evidence suggesting that exposure may promote the abnormal build-up of beta-amyloid plaques and tau protein tangles, which are linked to Alzheimer’s, while also increasing biological stress pathways associated with Parkinson’s disease progression. While direct causal relationships are still being studied, scientists believe the evidence strongly indicates that microplastics can aggravate existing neurodegenerative conditions.

Supporting evidence has emerged from separate research published in Nature Medicine, which revealed that microplastics are more concentrated in brain tissue than in any other major organ. The study found an average of 4,800 micrograms of microplastics per gram of brain tissue — comparable in plastic content to a standard plastic spoon. This discovery has reinforced growing fears about the long-term neurological risks of everyday plastic exposure.

Experts are now urging the public and policymakers to take the findings seriously, as plastic pollution is becoming an unavoidable part of modern life. Microplastics have been detected in processed foods, bottled drinks, seafood, salt, tea bags, household dust, soil and synthetic clothing fibres, making human exposure widespread and difficult to avoid.

The study recommends practical steps to reduce risk, including limiting the use of plastic food containers and cutting boards, reducing consumption of highly processed and packaged foods, avoiding synthetic fabrics where possible, and minimising the use of appliances that release microfibres into the air.

As plastic pollution continues to infiltrate ecosystems and the human body, the research highlights an urgent need for stronger environmental regulations, improved waste management systems and greater public awareness. While more investigation is required to fully establish long-term cause-and-effect relationships, the growing body of evidence suggests that reducing plastic exposure could be a critical step in protecting brain health and lowering the future burden of neurodegenerative disease.