What causes autism?

Photo by Blaise Vonlanthen on Unsplash

Amber Tanski


Recent studies have shown that 1 in 6 children in the United States are born with developmental disabilities. Autism is one of the most common with a prevalence rate of 1 child per 59 as of 2018. Autism spectrum disorder is a congenital disorder characterized by atypical social interactions, communication deficits, and the presence of repetitive or stereotyped behaviors. Because it covers a wide range of conditions, there is no single explanation as to what causes it.

One thing we know for certain is that vaccines do not cause autism (Chung, 2014). This common misconception started with a fraudulent research study that was later retracted from the original journal it was published in. The ingredients in vaccines have been tested and proven safe through many scientific studies conducted over the last few decades. A list of these studies is located at healthychildren.org.

Researchers suggest that the development of autism may be caused by a combination of environmental and genetic factors. Wendy Chung, director of clinical research at the Simons Foundation Autism Research Initiative, discusses the role these factors play in her Ted Talk, Autism – what we do know (and what we don’t know).

In her talk, Chung explains how autism is in part hereditary. When compared to other diseases and disorders, such as cancer or diabetes, it has the highest heritability rate. This is demonstrated by its high concordance rate, which is the probability that if one sibling has autism that another sibling in the family has autism. For example, in identical twins, there is a 77% chance that one child will develop autism if his identical twin has. While this percentage shows that certain genes causing autism may be inherited, it also indicates that it is not the only reason autism occurs.

A genetic mutation in a sperm or egg may result in a child being the first in his family to develop autism. This information can be used to understand and identify the genes causing autism in those individuals. The Simons Simplex Collection conducted a study consisting of 2,600 individuals that had no family history of autism. They looked at the genetic differences between the child and his parents. By analyzing their genetic makeup, researchers identified De Novo mutations as the cause of 25% of autism.  There are an estimated 200-400 genes that have also been proven to cause it, which explains why the effects vary so greatly.

Along with genetic factors, there is a collection of environmental factors that may be involved. One of the most important risk factors is advanced paternal age. If the father is older than 34 years of age, there is a greater chance that the child will have autism, with the risk increasing by 29% for every 10-year increase in fathers’ age (Karimi et al, 2017). Another risk factor is exposure to certain drugs and environmental toxins during pregnancy, a vulnerable and critical period of development. One pharmaceutical expecting mothers should avoid is valproic acid, a medication mothers with epilepsy sometimes take. They should also stay away from certain chemicals like pesticides and phthalates (commonly found in plastics).

There is so much we still don’t know about autism spectrum disorder and what causes it, which is why Wendy Chung invites you to join the Innovative Autism Network. This is a collective effort to improve the lives of people with autism by increasing our understanding of and experience with the disorder.

Do you work with children with autism?

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Amber Tanski is a Content Marketing Specialist for DrOmnibus, a company creating  ABA DrOmnibus – Resources App – All in one tool with a direct focus on resources for therapy, including baseline assessment, in-built and personalized ABA programs, graphs  and video modeling.  After graduating with a Bachelor of Science in Kinesiology, Amber has worked with a diverse population through her job as a Line Therapist for young children with Autism, being a Personal Trainer for a girl with Asperger’s Syndrome and working as a Personal Care Assistant for a woman with Muscular Dystrophy. She currently develops content for DrOmnibus utilizing her unique experience.


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