João Xavier Santos, researcher of the Biomedical Research Group at the National Institute of Health Dr. Ricardo Jorge, is the first author of a new paper – coordinated by Astrid Vicente, leader of the same group –  that was published in the journal Environmental Research. In the BioISI Digest below get to know more about this study, on which the effect of the exposure to particulate matter by pregnant women is associated with the severity of Austism Spectrum Disorder (ASD) found in their babies.

What was the starting point that led to the current research?

Autism Spectrum Disorder (ASD) is a clinically heterogeneous neurodevelopmental disorder, and heritability estimates of 50-80% suggest that both genetic and environmental factors have a role in its etiology. Multiple studies have shown that exposure to air pollutants, including particulate matter (PM_2.5 and PM₁₀), nitrogen dioxide (NO₂), sulfur dioxide (SO₂) and ozone (O₃), during pregnancy and first year of life, contributes to the risk of developing ASD. However, there is few data regarding a role of exposure to air pollutants in clinical severity. Our objective was to understand if higher exposure to air pollutants during critical neurodevelopmental windows leads to a higher clinical severity.

What is the main finding reported in this paper?

Air quality monitoring data from the Portuguese Environment Agency was used to estimate exposure to air pollutants in 217 subjects with ASD, born in Região Centro of Portugal between 2003 and 2016. These subjects were clinically stratified in two subgroups according to clinical severity: milder and higher severity. The main finding of this work was that exposure to PM_2.5 during the first trimester of pregnancy and full pregnancy, and to PM₁₀ during the third trimester of pregnancy is associated with a higher clinical severity of ASD.

If you had to explain the main finding to a 5-year-old child, how would you do it?

We looked at something called particulate matter. These are tiny particles in the air that we can’t see because they’re very small. We found that when mothers were pregnant, and they were exposed to these tiny particles, it might make autism a little bit more severe in their children. Autism is a way some people’s brains work differently, and it can affect how they understand and interact with the world.

Why is it important for the scientific community and for society at large?

This work reinforces the role of exposure to air pollutants in ASD risk, and provides novel evidence for an impact in clinical severity of the disorder. This points towards the existence of risk factors specific to clinical subgroups of ASD. Our results highlight the importance of air quality for a healthy neurodevelopment and for the risk of severe neurodevelopmental disorders. In the future, this may help in the implementation of public health strategies for ASD prevention.

What are the next steps?

Given that ASD etiology involves gene-environment interactions, we are now working towards the integration of genetic and environmental data, in order to obtain a more complete picture of the mechanisms behind this complex disorder. It is also necessary to explore the biological mechanisms by which exposure to particulate matter can modulate ASD clinical severity, which can be done through laboratorial assays.

From left to right: Astrid Vicente and João Xavier Santos [photos provided by the authors]

Discover about the GEnvIA  project, on which this investigation was developed,  here. 

Read the full paper here.