What Does (and Does Not) Cause Autism
In the past few weeks we’ve talked a lot about recognizing autism, starting therapy, and getting tested for autism. But what causes autism? Can it be avoided, or screened for? The developing understanding of autism is one of my special interests, so let me share a brief overview of what I’ve learned while hopefully putting some of the more harmful false information to bed:
Genetics
While genetics definitely play a factor in autism (you are more likely to be autistic if you have an autistic family member), there is no one “autism gene.” That being said, researchers have, so far, identified about 100 genes that are strongly linked to autism. Most of them affect communication between neurons in the brain (more on that towards the end of this article). Additionally, some genetic conditions and deletions are associated with a higher risk for autism, such as fragile X syndrome. This article has a nice overview of the genetics affecting autism, as well as some links to further reading.
Environmental Factors
Even less understood than the role of genetics in autism is the role of environmental factors in autism. I want to stress that right now all scientists can prove is correlation, not causation. In other words, some of these environmental factors happen at the same time as autism, but cannot be definitively proven as a primary source. These environmental factors include: advanced parental age at time of conception, exposure to pollution (especially pesticides), a mother’s immune response to a virus or other infection during pregnancy, maternal health during gestation (mothers with diabetes, immune disorders, and obesity have a higher rate of children with autism), and pregnancy and birth complications such as low birth weight, premature delivery, and oxygen deprivation.
At this time, scientists can only say that autism is probably caused by a combination of factors. Say, genetic predisposition and older parents in one case, or premature birth and fragile X syndrome in another. There is no way to avoid your child “getting” autism, it is just something that happens. Really the only thing you can do is make the healthiest choices available to you during conception and pregnancy…but even then it is ultimately out of a mother’s control as to whether she gets the flu while pregnant or what pollution levels are in the air on any given day. So if you suspect autism in your child or have just received a diagnosis of autism, put your mom guilt aside. It is just something that happens. To that end…
Things that do Not Cause Autism
There are two major things that do NOT cause autism. That is a “refrigerator mother” and vaccines. Let’s start with the refrigerator mother, which, I hope, has been largely left in the garbage heap of history, but may rear its head from time to time (especially from a judgmental elderly onlooker or particularly out of touch doctor). The Refrigerator Mother Theory, or Bettelheim’s Theory of Autism (so-named after the doctor who established its popularity) was coined in the 1940s. This theory claimed that autistic behavior in children was caused by emotional distance and coldness on the mother’s part. This caused many mothers from the 40’s to the 70’s to suffer blame, guilt, and even give in to coerced separation from their children. Of course emotional abuse does, sadly, happen sometimes between a mother and a child, and in cases of true abuse, autistic behavior indicating or coping with stress may be exacerbated. Abuse cases aside, this theory has been thoroughly debunked by the scientific community.
Vaccines are another common scapegoat for autism. There is a good Snopes article that goes through the problems with the redacted survey study done in 2016 that caused a big kerfuffle. Additionally, the 1998 study that claimed the MMR vaccine was to blame for autism only looked at 12 individuals and was later labeled as fraud. At this time there is no scientific proof that vaccines of any sort cause autism. Studies done by The CDC, the Immunization Safety Review Committee of the Institute of Medicine, as well a as a myriad of international studies published by reputable journals have all found no link between vaccines and autism.
I want to mention one more “culprit” that seems to be gaining some alarming traction: There are claims that acetaminophen (Tylenol) taken during pregnancy may cause autism. I myself have received targeted ads for class-action lawsuits and settlements related to this claim, and personally believe this is a case of unscrupulous people seeing a dollar to be made off of desperate and scared parents. I want to stress, strongly, that nothing definitive has proved that acetaminophen use causes autism. That being said, I think it is gaining traction because of the correlation between acetaminophen use and autism (again, correlation, not causation). Acetaminophen is THE over-the-counter pain medication recommended to pregnant women, so lots of women take it while pregnant. I took it during both my pregnancies, and yet only one of my kids turned out autistic. What is most likely (though is also awaiting scientific proof), is that whatever was causing a pregnant individual to take acetaminophen — a viral infection causing aches, pains, and fever, for example — is more likely a contributing factor in autism.
Brain Physiology
As I’ve mentioned before, at this time there is no medical test — such as blood test, genetic screening, or MRI — that can identify an autistic individual. However, that may change in the future because researchers are finding some very interesting and measurable differences in the autistic brain. For example, autistic individuals have more neural connections in the frontal and parietal cortex (areas that control complex thought) but fewer neural connections in sensorimotor and temporal cortex (areas that control movement and processing stimuli). Autistic individuals also may have less connectivity between the two hemispheres of the brain, which may cause them to struggle with some aspects of communication. This lower connectivity between hemispheres is not exclusive to autism, though, and needs more research.
More concrete evidence backs up autistic individuals having enlarged amygdala (the area of the brain responsible for fear responses, amongst other things). This has been observed in school-aged children for some time, but a recent study has found that it is even present in infants. This is exciting, because it may lead to earlier diagnosis, which means earlier support and interventions. Also, if a physiological difference is pinpointed, it may be possible to come up with targeted therapies down the road to address these differences.
Broader Autism Phenotype
While not really a cause, I do want to mention a relatively new term that I’ve seen pop up from time to time: Broader Autism Phenotype, or BAP. Apparently the term has been around since at least 2011, and recognized as a phenomena since 1943 or earlier, but it seems to be gaining some popular traction recently. BAP describes sub-clinical autistic traits. Basically, a person that is “kind of” autistic. As the parent of an autistic child, and knowing that genes at least play a role in autism, this designation makes sense to me.
I would never claim to be autistic, but a lot of Emmy’s* “autistic” behavior is similar to some things that I did as a kid or even now. For example, I was always described as “aloof” or “shy” as a child. It’s not that I didn’t like other kids, I just was unsure how to act around them. Emmy is the same. Additionally, I’ve always shook my hands, as in, rapidly shaking them back and forth like I’m trying to shake something off them. Usually it is in some socially acceptable context, like, after hearing or seeing something gross, or when I’m finished with a task I’ve been working hard on. Emmy also has similar stims. I can get absorbed in a project to the detriment of other areas in my life (when I took a jewelry-making course in college I literally spent 12 hours a day in the studio every single day). Woe to the person who tries to interrupt Emmy when she is in a play flow. Also, it turns out that both my father (Emmy’s grandfather) and my husband (Emmy’s father) engaged in behaviors that could be described as “repetitive and restrictive” as a form of self-comfort when they were children, but neither of them are autistic, either.
Looking Forward
There is still so much we don’t understand about the brain, genes, and autism. We have made some wonderful strides both in patient care and in medical understanding of individuals with autism, but there is so much more to be learned. I’m hoping, as more children (and late-diagnosed adults) receive their diagnosis, there will be a stronger push to understand autism more, to normalize harmless autistic behavior, and to have supports become more standard in schools, the workplace, and other high-use spaces like grocery stores. Some people are worried that identifying an “autism gene” or other screening that could be done in utero would lead to autistic babies being aborted. While that concern can’t be discounted completely, I think we are a long way off from that, yet. I personally support genetic and brain research in the hopes that earlier identification of autistic individuals will lead to earlier support, and that earlier support will improve the quality of life for both the autistic individual and their family. As our understanding (and acceptance) of autism increases, so does the ability for autistic individuals to live happy and fulfilling lives as valued members of society. I look forward to seeing what new things are discovered in the coming decades.
*names have been changed.
Annie Newman is a substitute teacher, mom, and aspiring children’s book author raising two children: one neurotypical and one autistic. You can also follow her day-to-day learning on Instagram and on Tiktok.