Modena, Italy – What are nanoplastics and microplastics doing in the cerebrospinal fluid of people with ALS? And how did they manage to reach the brain?
These are among the questions researchers at the University of Modena and Reggio Emilia (Unimore) are now investigating after identifying and measuring plastic particles in the central nervous system of people with amyotrophic lateral sclerosis (ALS) as well as individuals without the disease.
The most significant finding is that concentrations of these particles in the cerebrospinal fluid (CSF)—the clear liquid surrounding the brain and spinal cord—were, on average, higher in patients with ALS. The association appeared particularly noteworthy for the smallest particles.
The study was published in the scientific journal Brain Communications.
The research was coordinated by Marco Vinceti, an epidemiologist at Unimore, and Jessica Mandrioli, a neurologist at the same university.
Vinceti explained that the presence of these particles in cerebrospinal fluid could point to possible neurotoxic activity, particularly in the case of the smallest particles. He has raised the hypothesis that nanoplastics might behave as a kind of “Trojan horse,” potentially facilitating the transport of harmful substances—such as heavy metals, selenium, cadmium and lead—or triggering mechanisms that could ultimately damage neurons.
However, Vinceti stressed that these remain hypotheses that will need to be tested.
Mandrioli, together with Giulia Gianferrari and Roberta Bedin, highlighted the translational nature of the research and the need to expand it. The goal is not simply to detect plastic particles, but to determine whether—and how—this type of exposure might be involved in the biological mechanisms underlying ALS.
What Is ALS?
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting motor neurons, the nerve cells responsible for controlling voluntary muscles.
As these neurons degenerate, muscles progressively lose their ability to receive the signals required for movement. This leads to weakness, loss of muscle strength and mass, and increasing difficulty with movement. As the disease progresses, patients may also develop problems with swallowing, speech and breathing.
ALS does not have a single known cause. A relatively small proportion of cases are associated with inherited genetic mutations, while most patients have what is known as sporadic ALS.
This large unexplained area of the disease is one of the reasons researchers continue to investigate possible environmental factors and the interactions between genetic predisposition and repeated environmental exposures over the course of a lifetime.
Microplastics and Nanoplastics: Why Size Matters
Microplastics are microscopic fragments of plastic material, while nanoplastics are even smaller, typically measured on the nanometer scale or below one micrometer.
The difference is not simply a matter of size. Extremely small particles may have a greater ability to interact with cell membranes, proteins and other biological components.
This makes their presence in the central nervous system particularly significant from a research perspective.
The brain is protected by the blood-brain barrier, a highly selective structure that restricts the passage of many substances from the bloodstream into nervous tissue. Cerebrospinal fluid, by contrast, is in direct contact with the brain and spinal cord, making it an especially important biological compartment for studying processes involving the central nervous system.
However, finding these particles in cerebrospinal fluid does not demonstrate that they have damaged motor neurons.
This distinction is essential to interpreting the study correctly: the researchers identified an association, not a causal relationship.
From the Laboratory to the Clinic
One of the most technically challenging aspects of the study was identifying extremely small quantities of plastic particles within biological samples.
Researchers from the University of Catania, coordinated by Margherita Ferrante and Gea Oliveri Conti, contributed expertise and methodologies for detecting and measuring nano- and microplastics. Lauren Wise, an epidemiologist at the Boston University School of Public Health, also participated in the research.
The study therefore goes beyond the question: “Is there plastic in the nervous system?”
The next question is considerably more complex: What happens when these particles interact with the human body, and could they play a role in the biological processes that precede motor-neuron degeneration?
One hypothesis concerns oxidative stress, an imbalance between the production of oxidizing molecules and the body’s ability to neutralize them.
Other possibilities involve neuroinflammation, the activity of glial cells and potential alterations in mitochondrial function.
All of these mechanisms are already being studied in ALS. However, the fact that they are compatible with some of the possible biological effects of microplastics and nanoplastics does not mean that this new study has demonstrated a connection between plastic exposure and ALS.
The Environmental Hypothesis
Research into the causes of ALS already includes a broad range of hypotheses involving environmental factors.
Over the years, scientists have investigated occupational exposures, pesticides, metals, air pollution and other environmental factors. Findings have not always been consistent, and no single environmental factor can currently explain the majority of ALS cases.
One particularly important concept is the exposome: the totality of environmental exposures an individual experiences throughout life.
From this perspective, a disease such as ALS could potentially result from interactions between a person’s genetic characteristics and multiple environmental exposures occurring at different stages of life.
Research into microplastics and nanoplastics therefore fits into an already established scientific framework, adding another potential variable that now needs to be investigated.
Genetics also remains a fundamental part of ALS research. Numerous genetic variants associated with the disease have been identified, and certain mutations explain some familial forms of ALS.
Yet genetics alone does not provide a complete explanation, particularly for sporadic cases. Much of contemporary research therefore focuses on the complex intersection between the genome, the environment and individual vulnerability.
The “Trojan Horse” Remains a Hypothesis
The hypothesis proposed by Vinceti, together with Tommaso Filippini and Teresa Urbano, that nanoplastics could act as a kind of “Trojan horse” is particularly interesting because it shifts attention away from the mere physical presence of plastic particles and toward their potential biological role.
A nanoplastic particle could, in theory, interact with other substances present in the environment or the human body and alter how those substances behave.
But researchers still need to determine whether such a mechanism actually occurs in the nervous system—and, crucially, whether it has any relationship with ALS.
This is where the research will need to go next.
Larger cohorts, longitudinal studies and more detailed biological analyses will be necessary to establish whether higher concentrations of these particles precede the onset of ALS, accompany its progression, or instead arise as a consequence of metabolic or behavioral changes associated with the disease.
For Mandrioli and Vinceti, detecting these particles in cerebrospinal fluid therefore represents the beginning of an investigation rather than its conclusion. The aim is to continue studying nanoplastics in order to better understand the mechanisms that may contribute to the development of ALS, one of the major unresolved questions in neurology.
An Association, Not Proof of Causation
The key message from the study is not that nanoplastics cause ALS. At present, there is no evidence that allows researchers to draw that conclusion.
What the study shows is that researchers have been able to document the presence of nano- and microplastics in human cerebrospinal fluid and that, among the ALS patients included in the study, concentrations were higher on average.
The findings will need to be confirmed in larger populations and investigated through further research.
Nevertheless, the discovery is significant enough to introduce a new avenue of investigation into the possible causes and biological mechanisms of a disease that, in the majority of cases, still lacks a definitive explanation.
References
- Vinceti M, et al. Central nervous system concentrations of nano- and microplastics and risk of amyotrophic lateral sclerosis. Brain Communications. 2026. DOI: 10.1093/braincomms/fcag296.
- Goutman SA, Savelieff MG, Jang DG, Hur J, Feldman EL. The amyotrophic lateral sclerosis exposome: recent advances and future directions. Nature Reviews Neurology. 2023;19:617-634.
- Nijs M, Van Damme P. The genetics of amyotrophic lateral sclerosis. Current Opinion in Neurology. 2024;37(5):560-569.
Contact
Prof. Marco Vinceti