Study Links Severe Childhood Illness with Autism

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Autism Spectrum Disorder (ASD) is a developmental disability that affects the brain as it grows and can lead to social and behavioral issues. According to the U.S. Centers for Disease Control and Prevention (CDC), 1 in 54 children has been diagnosed with ASD and boys are about four times as likely as girls to be autistic. [1] While a single cause of autism isn’t known and likely doesn’t exist, what scientists do know is that changes to certain genes in someone’s DNA (called mutations) can make it more likely that an individual will show symptoms of autism. The question that remains, however, is: why do some people with these gene mutations develop ASD and others do not?

It’s been known for a while that a pregnant person getting sick can increase the risk of ASD in their baby. In a study published September 17 in the journal Science Advances, Manuel López Aranda, Alcino Silva, and colleagues found that severe illness after birth may also increase the risk of autism. They showed that young male mice that experienced inflammation—a reaction that the body usually has to severe disease—demonstrated ASD-like behaviors after they grew up. [2] The researchers were able to determine in the mice that the cells responsible for the change in the animals’ behavior as they aged were microglia, the immune cells that live in the brain and are responsible for cleaning up cellular debris and waste products.

Researchers often use animals like mice to ask questions about biology because they’re easier to study than people and allow scientists to do many more and more varied experiments than would be ethical in humans. Often, a research team stops with the animal work and leaves any work in people to be done by another group with more expertise. In the case of this paper, though, the researchers continued their study into people, looking a database that contains the hospital records of more than 3.5 million children. When they looked at those hospital records, the team also found a link in male children between hospitalizations for severe infections when they were between 18 months and four years old and later ASD diagnoses, meaning the link between severe inflammation in early life and autism appears to extend to people as well.

“This paper has to be [understood] as proof that you need to vaccinate your kids,” coauthor López Aranda told the online news source The Scientist about the work. [3] The vaccinations not only protect from the complications of severe disease, which can include death, but also protect against inflammation that could tip the balance toward the development of autism for a child who is already at risk.

What should I do if I suspect my child is autistic? 

If you think your child might be autistic, the first thing to do is to speak with their pediatrician. Doctors who specialize in the care of children know what to look for in terms of what is developmentally typical and what is not. If you have a gut feeling that your child has a developmental disability and you don’t feel like your child’s doctor is listening to you, seek a second opinion, potentially from a so-called developmental pediatrician, who may have more expertise in atypical child development.

According to the CDC, it is possible to receive a diagnosis of autism as early as 18 months and a very reliable diagnosis by 24 months. [4] If your baby is doing any of the following potential early ASD signs, it’s not a bad idea to have a conversation with your pediatrician about them, as they can be an indicator of social challenges that may persist through growth and development:

  • Not making eye contact
  • Not taking interest in other people
  • Less use of language or communicative sounds than peers of the same age and stage
  • Responding with discomfort and inflexibility when the daily routine is changed
  1. “Data & Statistics on Autism Spectrum Disorder,” CDC.
  2. F. López Aranda et al., “Postnatal immune activation causes social deficits in a mouse model of tuberous sclerosis: Role of microglia and clinical implications,” Science Advances, doi:10.1126/sciadv.abf2073, 2021.
  3. “Serious Infections Linked to Autism: Study,” The Scientist, 2021.
  4. “Screening and Diagnosis of Autism Spectrum Disorder,” CDC.
Abby Olena
Dr. Abby Olena has a PhD in Biological Sciences from Vanderbilt University. She lives with her husband and children in North Carolina, where she writes about science and parenting, produces a conversational podcast, and teaches prenatal yoga.

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