Environmental exposure to air pollutants during critical developmental periods may significantly impact autism risk, according to a groundbreaking Emerging Topic review published in Brain Medicine on 12 November 2024. The study reveals how common air pollutants, including fine particulate matter and nitrogen oxides, can trigger complex biological cascades affecting brain development.
“Various neurological disorders, including autism spectrum disorder, can be linked to this environmental factor,” explains Professor Haitham Amal from the Hebrew University of Jerusalem, who is the senior author of the study. “The timing of exposure is critical, as there is a heightened vulnerability during prenatal development and early childhood when essential neurodevelopmental processes occur.”
The review identifies several critical pathways through which air pollutants may influence autism development:
• Nitrosative stress orchestrated by nitric oxide (NO)
• Neuroinflammation and oxidative stress
• Disruption of neurotransmitter systems
• Epigenetic modifications
• Endocrine system interference
• Metabolic pathway dysregulation
Of particular concern is the finding that smaller particles, especially PM2.5 and NO products, can cross the placenta and affect fetal brain development. This revelation raises important questions about protective measures for pregnant women in highly polluted areas.
“The research suggests that individuals with genetic predisposition to ASD may be more vulnerable to the harmful effects of air pollution exposure,” Professor Amal notes. “This interaction between genetic and environmental factors opens new avenues for understanding ASD’s complex aetiology.”
“My lab has shown that NO plays a major role in autism. However, this study emphasizes the critical role of this molecule and its derivatives on the brain,” Prof. Amal comments.
The review, first authored by PhD student Shashank Ojha, also highlights promising directions for biomarker development, potentially enabling early identification of at-risk individuals. These findings arrive at a crucial time, as global autism prevalence reaches 1-1.5% of the population.
The implications extend beyond individual health to public policy. How might cities need to adapt their urban planning to protect vulnerable populations? What role could air quality monitoring play in prenatal care? These questions become increasingly urgent as urbanization continues worldwide.