From the Guidelines
The exact causes of autism spectrum disorder (ASD) remain unknown, but research suggests it results from a combination of genetic and environmental factors, with genetic factors playing a significant role, as identified in a 2019 study published in Environmental Health Perspectives 1. Genetic factors play a significant role, with hundreds of genes potentially contributing to autism risk, especially those involved in brain development and neuronal communication. Environmental influences during pregnancy may include advanced parental age, maternal illness during pregnancy, certain medications taken during pregnancy, premature birth, and low birth weight. Some key points to consider include:
- Genetic testing, including chromosomal microarray analysis, is warranted and clinically indicated for all suspected cases of ASD, as recommended in a 2014 study published in Nature Reviews Neurology 1.
- The role of rare genetic variants supports the relevance of studying monogenic disorders, such as tuberous sclerosis complex, for understanding ASD pathophysiology, as discussed in a 2014 study published in Nature Reviews Neurology 1.
- Environmental chemicals, such as pesticides, heavy metals, bisphenol A (BPA), and phthalates, may contribute to the etiology of ASD, as suggested in a 2019 study published in Environmental Health Perspectives 1.
- Contrary to widespread misinformation, vaccines do not cause autism - this has been conclusively disproven by numerous large-scale studies. Autism typically appears in early childhood and affects brain development, particularly in areas controlling social interaction, communication, and behavior. The condition varies widely in severity and presentation, creating a spectrum of symptoms and abilities. Research continues to improve our understanding of autism's complex origins, with the hope that better knowledge will lead to improved interventions and supports for affected individuals, as discussed in a 2014 study published in the Journal of the American Academy of Child and Adolescent Psychiatry 1.
From the Research
Causes of Autism
The causes of autism are complex and multifaceted, involving a combination of genetic, environmental, and epigenetic factors.
- Genetic factors: Studies have identified hundreds of genes that contribute to the development of autism spectrum disorder (ASD) 2, 3, 4.
- Environmental factors: Exposure to environmental factors, such as prenatal and postnatal toxins, has been linked to an increased risk of developing ASD 2, 3.
- Epigenetic factors: Epigenetic modifications, which affect gene expression without altering the DNA sequence, have also been implicated in the development of ASD 3, 4.
- Gene-environment interactions: The interaction between genetic and environmental factors is thought to play a crucial role in the development of ASD, with genetic variants influencing an individual's susceptibility to environmental toxins 2, 3.
Genetic Causes
Genetic studies have identified several genetic variants that contribute to the development of ASD, including:
- Copy number variations (CNVs): CNVs, which involve the deletion or duplication of genetic material, have been linked to an increased risk of developing ASD 3, 4.
- Single nucleotide polymorphisms (SNPs): SNPs, which involve a single nucleotide change in the DNA sequence, have also been implicated in the development of ASD 4.
- Epigenetic alterations: Epigenetic alterations, such as DNA methylation and histone modification, have been linked to changes in gene expression and the development of ASD 3, 4.
Environmental Causes
Environmental factors, such as:
- Prenatal exposure to toxins: Exposure to toxins during pregnancy has been linked to an increased risk of developing ASD 2, 3.
- Postnatal exposure to toxins: Exposure to toxins after birth has also been linked to an increased risk of developing ASD 2, 3.
- Sensory processing difficulties: Sensory processing difficulties have been linked to an increased risk of developing ASD, and sensory integration therapy has been proposed as a potential treatment 5.