Title:Environmental Risk Factors in Autism Spectrum Disorder: A
Narrative Review
Volume: 31
Issue: 17
Author(s): Konstantin Yenkoyan*, Meri Mkhitaryan and Geir Bjørklund*
Affiliation:
- Neuroscience Laboratory, Cobrain Center, YSMU, Yerevan, 0025, Armenia
- Department of Research,
Council for Nutritional and Environmental Medicine, Mo i Rana, Norway
Keywords:
Autism spectrum disorder, epidemiology, risk factors, environmental factors, toxic metals, pregnancy.
Abstract: Existing evidence indicates that environmental factors might contribute up to
50% of the variance in autism spectrum disorder (ASD) risk. This structured narrative review
offers a comprehensive synthesis of current knowledge on environmental risk factors
in ASD, including evaluation of conflicting evidence, exploration of underlying
mechanisms, and suggestions for future research directions. Analysis of diverse epidemiological
investigations indicates that certain environmental factors, including advanced
parental age, preterm birth, delivery complications, and exposure to toxic metals, drugs,
air pollutants, and endocrine-disrupting chemicals, are linked to an increased ASD risk
through various mechanisms such as oxidative stress, inflammation, hypoxia, and its
consequences, changes in neurotransmitters, disruption of signaling pathways and some
others. On the other hand, pregnancy-related factors such as maternal diabetes, maternal
obesity, and caesarian section show a weaker association with ASD risk. At the same
time, other environmental factors, such as vaccination, maternal smoking, or alcohol consumption,
are not linked to the risk of ASD. Regarding nutritional elements data are inconclusive.
These findings highlight the significance of environmental factors in ASD
etiology and emphasize that more focused research is needed to target the risk factors of
ASD. Environmental interventions targeting modifiable risk factors might offer promising
avenues for ASD prevention and treatment.