Researchers at the University of Minnesota recently discovered the most compelling evidence to date that girls present with different symptoms of autism spectrum disorder (ASD) compared to boys - highlighting the need for new and innovative approaches to improve diagnostic practices.
For decades, autism researchers have sought to understand the differences and similarities between autistic males and females. ASD is commonly considered a male-dominant condition, with three to four males diagnosed for every female. Females are also typically diagnosed later than males. Research led by Dr. Casey Burrows, an associate professor in the Medical School on the Twin Cities campus and licensed psychologist at the Masonic Institute for the Developing Brain, analyzed data spanning 18 years and over 4,000 participants to investigate potential sex differences in autism symptoms in children. This study followed younger siblings of autistic children, who are at higher likelihood of developing autism themselves. This method reduces bias caused by studies that only focus on children who come to clinical attention on their own. The research sheds light on why females are underdiagnosed and offers recommendations on how to improve early identification.
The study, published in JAMA Network Open, found:
- ASD traits can present differently in males and females.
- Notably, females showed fewer issues with eye contact - a key early marker of ASD - than males.
- When researchers accounted for sex differences in how autism is best measured, females had milder symptoms.
- Many existing studies only include children who are already diagnosed, missing girls who go undetected during early screenings and perpetuating diagnostic bias.
"Sex-related biases are likely baked into the current ASD identification system," said Burrows. "We think there are more females exhibiting autism-related concerns than epidemiological estimates would lead us to believe, and we want to improve early detection for these females. For example, our findings show that females are less likely to show difficulties with eye contact, which is probably the best-known autism symptom. It's no wonder then that we're missing autism concerns in females."
Current diagnostic thresholds do not account for sex differences, but implementing sex-specific thresholds may improve early identification for girls. Burrows advocates for a shift in research practices, including recruitment methods that reduce bias - such as sampling children with a family history of autism - and expanding diagnostic criteria to include traits that are more common in females, like milder difficulties with eye contact and inflexible behaviors.
"Typically developing girls and boys show differences in their language and social development," said Jed Elison, a professor in the College of Education and Human Development and co-author of the paper. "It makes sense that we should take those differences into account when studying something like autism, which is defined by social challenges and is often accompanied by language delays."
