Blood-brain barrier and mechanical cell damage
Table of Contents
It starts with mechanical damage to our brain’s most important protective barrier, the blood-brain barrier. “Microplastics weaken this barrier and make it permeable,” explains Sia’s colleague Kamal Dua. “This activates immune cells and inflammatory messengers, which then cause even more damage to the cells of the blood-brain barrier.” As a result, gaps open in the barrier through which not only the plastic particles but also other substances can penetrate the brain.
If the microplastics are then distributed in the brain, the particles can cause direct mechanical damage to the sensitive neuronal structures: “It has been shown that microplastics can damage a wide variety of structures, including the myelin sheaths of the nerve fibers as well as the membranes and microtubules of the neurons,” report Sia and his colleagues. This can disrupt the conduction of stimuli and the function of brain cells.
Immune reactions and chronic inflammation
The plastic particles that penetrate the brain also trigger immune reactions. For example, if nanoplastics are absorbed by microglial cells – the phagocytes of the brain – this causes their activation, physiological changes and the release of inflammatory messengers, as studies show. The astrocytes of the brain also react to the foreign bodies and trigger further chronic inflammatory processes.
“Such chronic neuro-inflammation can promote the deposition of misfolded beta-amyloid proteins and tau proteins,” explain Sia and his team. The presence of microplastics disrupts the brain’s waste disposal – the processes through which defective cells and faulty molecules are broken down and flushed out. In mice, this even resulted in measurable behavioral changes and dementia-like symptoms.
Oxidative stress and impaired mitochondrial function
Another route of damage is oxidative stress: the plastic particles release aggressive, reactive molecules in the form of free radicals, which can damage cell structures and DNA, as studies on animals and cell cultures show. At the same time, the microplastics impair the natural protective systems against oxidative stress, which intercept such aggressive molecules and render them harmless, as the researchers report.
And finally, the nano and microplastics that penetrate the brain can also damage the mitochondria – the “power plants” of the brain cells. “The microplastics disrupt energy production by the mitochondria by reducing the supply of adenosine trisphosphate (ATP),” explains Dua. However, without the chemical energy of ATP, the cells can no longer fulfill their function adequately. “This lack of energy weakens neuronal activity and can even cause the cells to die,” says Dua.
“Urgent need for further research”
Taken together, these previous findings demonstrate that nano- and microplastics can damage our brains in direct and indirect ways. “These overlapping mechanisms underline the multifactorial and self-reinforcing nature of the brain’s exposure to microplastics,” the researchers state. However, they also admit that much of the knowledge gained so far is based on animal experiments and cell cultures.
“Given the growing prevalence and continued use of plastics in everyday life, there is an urgent need for further research into the neurological effects of microplastic contamination,” conclude Sia and his colleagues. (Molecular and Cellular Biology, 2025, doi: 10.1007/s11010-025-05428-3)
Quelle: Molecular and Cellular Biology, University of Technology Sydney
December 10, 2025 – Nadja Podbregar