A frequently used screening test for autism creates a gender gap that could hinder diagnosis and treatment for women and girls, a new study suggests.
Researchers who study autism have been working to include more women and girls in their studies in recent years. Still, the majority of these studies consistently include few or no female participants, the report authors said.
Why? They found that a screening test often used to decide who can take part in autism studies seems to exclude a much higher percentage of women than men.
"I think the findings favor having a more inclusive approach and widening the lens to end up being less biased in terms of who participates in research," said senior study author John Gabrieli. He's a professor of brain and cognitive sciences at Massachusetts Institute of Technology.
"The more we understand autism in men and women and nonbinary individuals, the better services and more accurate diagnoses we can provide," Gabrieli said in a university news release.
Diagnosis of autism is made based on things like repetitive behaviors and trouble with language and social interactions. Screening tests can help doctors figure out what's wrong, but they are not required to use them.
But autism studies typically use a screening test called the Autism Diagnostic Observation Schedule (ADOS) to decide who can take part in the research. This test measures social interaction, communication and repetitive behaviors. It gives a numerical score in each category, and only people who get a certain score can be included in studies.
With this latest research, lead study author Anila D'Mello, a former MIT postdoc researcher who is now an assistant professor at the University of Texas Southwestern, started to notice the test seemed to have different effects on men's and women's participation in research.
To learn more about these differences, D'Mello used an MIT database of autistic adults who have said they want to take part in studies, to try to find more female participants. But when she went through the subjects, she found that only about half of the women in the database met the test cutoff scores, while 80% of the men did.
"We were really surprised at how many males we retained and how many females we lost to the ADOS [test]," D'Mello said in the release.
The researchers then looked at more than 40,000 adults who had been diagnosed with autism in six public datasets, to see if this was a more common occurrence.
They found that the ratio of male to female participants in datasets that required ADOS screening was around 8:1. In datasets that only required an observational diagnosis, the ratio was between 2:1 and 1:1.
The findings were published recently in the journal Autism Research.
"The way we think about it is that the field evolved perhaps an implicit bias in how autism is defined, and it was driven disproportionately by analysis of males, and recruitment of males, and so on," Gabrieli said. "So, the definition doesn't fit as well, on average, with the different expression of autism that seems to be more common in females."
"Many females might be missed altogether in terms of diagnoses, and then our study shows that in the research setting, what is already a small pool gets whittled down at a much larger rate than that of males," D'Mello said.
"The goal is that research should directly inform treatment, therapies, and public perception," D'Mello said. "If the research is saying that there aren't females with autism, or that the brain basis of autism only looks like the patterns established in males, then you're not really helping females as much as you could be, and you're not really getting at the truth of what the disorder might be."
AutismSociety.org offers more on Autism Spectrum Disorder.
SOURCE: Massachusetts Institute of Technology, news release, Sept. 8, 2022