Higher microplastic levels seen in people with newly diagnosed ALS

A buildup of microplastics in the nervous system may be linked to a higher risk of developing amyotrophic lateral sclerosis (ALS), according to a new study.

People newly diagnosed with the neurodegenerative disease were found to have higher concentrations of tiny plastic particles in both their blood and the fluid surrounding their brain and spinal cord, known as cerebrospinal fluid (CSF), compared to those without the condition.

While the findings show a strong statistical association, they do not prove that microplastics directly cause ALS, researchers noted. It is possible that the disease itself leads the body to retain more plastic particles, or that environmental factors influence both plastic exposure and ALS risk. Nonetheless, the results highlight a critical area for further investigation into how environmental pollutants might trigger motor neuron damage.

“The observed pattern raises the possibility of a [disease-causing] role of nano- and microplastics in motor neuron degeneration and indicates higher CNS [central nervous system] concentrations of these chemicals in ALS cases,” researchers wrote.

The study, “Central nervous system concentrations of nano- and microplastics and risk of amyotrophic lateral sclerosis,” was published in Brain Communications. The work was supported by the Italian Ministry of University and Research.

Microplastics levels in blood and CSF

ALS is a disease in which motor neurons, the nerve cells that control movement, progressively degenerate and die. The exact causes of ALS are not fully understood, but a variety of factors, including genetic predisposition, lifestyle habits, and environmental exposures, are believed to influence disease risk.

Microplastics are tiny pieces of plastic that accumulate in the environment and in the human body. Nanoplastics are the smallest type of microplastics. Although lab models show that these particles can damage nerve cells in the brain and spinal cord, little research has explored their link to specific neurological conditions such as ALS.

In this study, researchers measured and compared microplastic levels in the blood and CSF of 24 people newly diagnosed with ALS and 20 people without the disease. Their goal was to investigate “the relation between CNS concentrations of nano- and microplastics … and the risk of [ALS].”

Results showed that median CSF microplastic levels among ALS patients exceeded 1,000 particles per milliliter (p/mL) for both men and women. Among those without ALS, median levels were below 300 p/mL in males and 700 p/mL in females.

ALS patients also showed higher median microplastic levels in their blood, though the variance between groups was less pronounced than in the CSF.

Statistical analyses showed an association between higher microplastic levels in the CSF and blood and an increased likelihood of having ALS, though the association in blood appeared only above a specific threshold.

“To our knowledge, the present study is the first to report higher nano- and microplastic concentrations in the CSF and serum of patients newly diagnosed with amyotrophic lateral sclerosis in a human population,” the researchers wrote.

The researchers also conducted analyses to examine associations between microplastic levels and disease progression patterns among ALS patients, but these analyses did not identify any statistically meaningful associations.

The scientists stressed that their findings do not prove that microplastics cause ALS. Other factors may also be at play. For example, other environmental exposures might affect both ALS risk and microplastic levels, or ALS itself might lead to greater accumulation of microplastics in the body. It’s also unclear whether different types of microplastics may affect the nervous system in different ways.

Still, because microplastics “could theoretically induce toxic mechanisms that either led to or triggered onset of [ALS],” the team concluded that further research into the role of microplastics in this disease is warranted.