This story by Jennifer Shutt appeared on Colorado Newsline on September 24, 2025. We are sharing it in two parts.
Health and Human Services Secretary Robert F. Kennedy Jr. stirred up major concerns and considerable speculation earlier this year when he announced the administration would release a report revealing the causes of autism by the end of September.
Kennedy, an environmental lawyer with no medical degree, stood next to President Donald Trump on Sept. 22 as they presented the over-the-counter drug Tylenol as one potential driving factor behind autism diagnoses and pointed to folate, a B vitamin, as a possible treatment — both conclusions the medical community hasn’t yet reached.
Kennedy throughout his tenure has also made overly broad and disparaging statements about people who have an autism diagnosis, often referring to traits exhibited in people with the most severe cases. For example, he claimed in April that children with autism would never function as independent adults, drawing intense criticism for making a generalization that would not apply to every person with a diagnosis.
The Trump-Kennedy announcement and Kennedy’s characterizations have raised questions about why someone would be diagnosed, what types of research have been done and what reputable science has found about causes.
States Newsroom spoke with three experts before the announcement to gain a better understanding of autism spectrum disorder. Below are brief excerpts from those interviews.
What is autism spectrum disorder?
The two core characteristics of autism are challenges with social communication and the presence of restrictive and repetitive behavior, according to Autism Science Foundation Chief Science Officer Dr. Alycia Halladay.
As understanding of the diagnosis has evolved, she explained, researchers and families have increasingly referred to it as autisms, plural, instead of autism, singular, in part, because there are so many different subtypes.
“It makes it more accurate when describing it — that autism is not just one entity of core autism features, that there is so much diversity across the spectrum, that it’s actually a group of developmental disorders,” Halladay said.
The spectrum, she said, ranges from people who may speak rarely to those who are fluent in language, people with cognitive disabilities to those with IQs of more than 120 and people who can live independently to those who need round-the-clock care.
Dr. Michael Murray, a professor in the Department of Psychiatry and Behavioral Health at the Penn State College of Medicine, described it as “a neurodevelopmental disorder, meaning that people are born with it and it’s lifelong and it can cause a variety of challenges for people.”
“The most common and significant and probably pervasive symptom across the spectrum is challenges in understanding and interpreting what we call neurotypical — meaning everyone who is non-autistic — social behavior,” Murray said. “So just understanding all the non-verbal parts of social communication, understanding nuance and non-literal use of language. All those things can be really difficult for autistic people.”
Approximately 1 in 31 children in the United States and 1 in 45 adults fall somewhere along the autism spectrum, according to the advocacy organization Autism Speaks.
How is autism diagnosed?
Only an expert can diagnose an autism spectrum disorder using criteria in a guide used by health care professionals called the Diagnostic and Statistical Manual of Mental Disorders, or DSM.
“You need someone who knows autism, who knows what to look for, who knows how to elicit behaviors or not elicit behaviors that are indicative of an autism diagnosis,” Halladay said. “So it’s really diagnosed by a psychiatrist, a psychologist, or somebody else who’s trained to understand what autism is and what it’s not.”
Murray said there are three social communication behaviors that doctors or other qualified medical professionals look for when considering whether to diagnose someone with autism.
“It is difficulty in interpreting social information. It is difficulty giving social information through things like facial expression and tone of voice. And thirdly, is a difficulty maintaining appropriate peer relationships,” Murray said. “Now, once again, this is from a neurotypical description of peer relationships. There’s a lot of talk among neurodivergent individuals about whether that’s fair, that we rate social relationships based on how we think they should be. But nonetheless, that’s the criteria.”
Murray explained experts also observe the presence of restrictive and repetitive behaviors in assessing whether someone has autism.
“And that captures things that are in the realm of interacting with the physical world around you,” Murray said. “So that need for sameness and inflexibility maintaining routines.”
Carissa Cascio, a senior scientist at the University of Kansas Life Span Institute and Kansas Center for Autism Research and Training, reinforced that autism is “strictly diagnosed based on behavior.”
“There are genes that have an association with autism that you can test for. There’s some genes that have a very strong association, and you can do a test for the presence of one of those genes,” Cascio said. “But for the diagnosis of autism itself, it’s strictly based on behavior.”
What do we know about the causes of autism?
While more scientific research is needed, a combination of genetics and environmental factors is responsible for the formation of autism spectrum disorders.
“We know that one of the largest causes of autism is genetics. We know this because it runs in families,” Halladay said, adding there “are over 150 known genes associated with autism.”
“If there’s a variation in the gene, there’s a high likelihood of having an autism diagnosis,” she said. “And those genes are genes that tell cells in the brain where to go and how to connect, which seems to be a core biological feature of autism.”
Halladay emphasized that research has established the “most important part is the interaction between genetics and the environment.”
“Neither the gene nor the environmental factor is strong enough, but together, they increase the probability of having a child with autism,” Halladay explained.
During the last 25 years, as Murray has advanced in his career, the medical community’s thinking about and understanding of autism spectrum disorders has “significantly increased.”
“We know right now that 80 to 90% of autism is accounted for by genetic differences …. It’s not just you got exposed to this thing in the environment, now you have autism. You have to have the genetic susceptibility first and then the environment might make it more likely, or maybe influence the expression of it,” Murray said.
Colorado Newsline is part of States Newsroom, a nonprofit news network supported by grants and a coalition of donors as a 501c(3) public charity. Colorado Newsline maintains editorial independence. Contact Editor Quentin Young for questions: info@coloradonewsline.com.