Higher concentrations of nano-and microplastics in the central nervous system may be associated with an increased risk of amyotrophic lateral sclerosis (ALS), according to a new Italian study.
Researchers measured plastic particles in blood serum and cerebrospinal fluid samples from 24 newly diagnosed ALS patients and 20 people without neurological disease.
The study, led by researchers at the University of Modena and Reggio Emilia and published in the journal Brain Communications, is the first to compare such concentrations between ALS patients and healthy controls.
Median microplastic concentrations in cerebrospinal fluid were nearly twice as high among ALS patients, at 1,022 particles per milliliter, compared with 532.1 particles per milliliter in the control group.
Serum concentrations were also higher among ALS patients, although the difference was smaller.
Researchers found that higher concentrations in cerebrospinal fluid were associated with greater odds of ALS, while serum concentrations were linked to the disease only above a certain exposure threshold.
Among ALS patients, higher serum concentrations were also associated with increased levels of neurofilament light chain, a biomarker of nerve-cell damage.
The findings raise the possibility that nano- and microplastics may contribute to motor neuron degeneration through direct toxic effects or through other pollutants carried by the particles, the researchers said.
However, study coordinator Marco Vinceti stressed that whether these contaminants cause toxic effects in the nervous system "remains to be conclusively determined.”
The researchers cautioned that the small case-control study could not establish causation or rule out "reverse causation” – the possibility that ALS-related changes led to greater accumulation of microplastics. Lifestyle differences or exposure to other chemicals may also have influenced the results.
ALS is a progressive neurodegenerative disease that damages nerve cells responsible for controlling voluntary muscle movement. Its underlying causes remain largely unknown.
