What research really says about autism

About two to three percent of all Americans—including adults and children—are autistic. With recent reports that autism rates are rising, potentially due to improved diagnosis, there’s a lot of conflicting information about the condition.

While research is ongoing to better understand autism, decades of work have established solid evidence about what causes autism and how to best support autistic people.

We spoke with epidemiologist Amanda Bakian, PhD, director of the Utah Registry of Autism and Developmental Disabilities, to find out what the science says about autism. 

What causes autism?

Autism is caused by genetics, Bakian says.

“Autism is a very heritable condition, so it really clusters in families,” Bakian says. “If a child is born into a family with autism, another sibling in the family has about a 20% likelihood that they might have autism as well.” Among identical twins, that likelihood increases to 60-90%.

So, is there an “autism gene”? Bakian says absolutely not. A large number of genetic differences, in many different places in human DNA, have been linked to autism, and for the large majority of autistic people, no single change causes their autism. Instead, it’s a combination of many DNA changes, each one of which is common in people without autism as well.

Environmental factors can also influence the likelihood of autism. Researchers are continuing to learn which conditions affect the likelihood that a child will be born with autism. But Bakian says that a lot of factors that can cause inflammation during pregnancy seem to have an effect. If someone has a high fever, such as from COVID infection, while pregnant, their child may be more likely to be autistic. Exposure to air pollution or heavy metals during pregnancy may have similar effects. But while some inflammation-related environmental factors have been linked to autism, their individual effects on autism are relatively modest.

Tylenol is safe to take during pregnancy and can help reduce fever.

How does research help autistic people?

Bakian leads a state-wide autism research effort, including a database designed to better understand the prevalence of autism and the needs of autistic people. The research database is not a registry and doesn’t track individual people with autism; rather, it keeps track of how common autism is in different regions and groups of people. This helps show places where autism may be underdiagnosed or that need more services to support people with autism. “This information is really critical to better serve autistic individuals and their families,” Bakian says.

Early and accurate diagnosis can help connect autistic people with resources that support each individual’s goals, whether that be applied behavior analysis, occupational therapy, physical therapy, educational services, or other resources.

Results from the state autism database have also led to better insurance coverage for medical costs related to an autism diagnosis.

“We have a much better understanding now of the kinds of services that could help autistic individuals thrive,” Bakian says. “What we really understand is that the earlier a child is identified with autism, and the earlier that child has access to services, the better the potential outcomes are.”

Will scientists find a cure for autism?

Bakian says that researchers aren’t looking for a cure for autism—and, she adds, they shouldn’t.

“There’s an interest and a need to understand what influences autism and the different aspects of autism,” Bakian says. “There’s a lot of strength in being autistic. There’s also a lot of aspects where people do benefit from access to services.”

Bakian emphasizes that, like all people, autistic people are individuals with highly individual traits and goals. Many autistic people see any supposed “cure” as a futile and undesirable attempt to change who they are as people. Therefore, responsible autism research focuses on how to better support autistic people and provide the services individuals may need to achieve their goals.

“We don’t see autism as being something to be cured,” Bakian says. “It’s something to be understood.”