Air pollution and ALS: a Swedish study reveals up to 30% higher risk of developing the disease

Prolonged exposure to air pollution could be linked to a higher risk of developing amyotrophic lateral sclerosis (ALS), according to research from the Karolinska Institute (Sweden) published in JAMA Neurology.

ALS is the most common disease within the group of motor neuron diseases, which cause the degradation of cells responsible for voluntary movement, leading to muscle atrophy and paralysis. It accounts for between 85% and 90% of cases of this type of disease.

Scientific Background

The causes of ALS are largely unknown, although scientists suspect that environmental factors influence its development.

Previous research had already indicated that poor air quality can cause inflammation and oxidative stress in the nervous system, which promotes neurodegenerative processes.

The Study in Sweden

The analysis included data from:

• 1,463 people with a recent diagnosis of motor neuron diseases.
• 1,768 siblings of patients.
• More than 7,000 controls from the general population.

The researchers studied the levels of particulate matter (PM) of three sizes (less than 2.5 microns, between 2.5 and 10 microns, and greater than 10), as well as nitrogen dioxide, at the participants’ residences up to 10 years before diagnosis.

Main Results

• The annual average values of pollutants were slightly above WHO guidelines.
• Prolonged exposure, even at relatively low levels like those common in Sweden, was associated with a 20% to 30% higher risk of developing ALS.
• People who lived in areas with higher pollution experienced a faster motor and pulmonary deterioration after diagnosis.
• These patients had a higher risk of death and a greater need for invasive treatments with a respirator.

Researchers’ Opinions

• Caroline Ingre, professor at the Department of Clinical Neuroscience at the Karolinska Institute:

  “Our results indicate that air pollution may influence not only the onset of the disease but also affect the speed at which it progresses.”

• Jing Wu, researcher at the Institute of Environmental Medicine:

  “We can observe a clear association between poor air quality and neurodegenerative diseases. Considering that pollution levels in Sweden are lower than in many other countries, our study underscores the importance of improving air quality.”

Study Limitations

The work is observational, so it cannot establish a definitive causal relationship. However, the results reinforce the hypothesis that air pollution is an environmental risk factor for the development and progression of neurodegenerative diseases such as ALS.

The study from the Karolinska Institute provides evidence that even relatively low levels of air pollution can have a significant impact on neurological health. The research underscores the need to improve air quality as a preventive measure against serious diseases and to advance environmental policies that reduce the population’s exposure to pollutants.