A simple eye exam gives new insights into why autism is often underdiagnosed in females.
About 1 in 36 children in the United States (U.S.) have autism spectrum disorder (ASD), with boys being nearly 4 times more likely to be diagnosed with the condition than girls. Moreover, females usually receive autism diagnosis later than males.
Growing evidence suggests that autistic girls quickly learn to mask their autism by copying others. Some research points to diagnostic bias that does not account for differences in how autism is expressed in boys and girls.
A new study published in the Journal of Autism and Developmental Disorders included 400 children aged 9 to 10 in New Zealand who exhibited a full range of possible autism traits.
The children underwent a variety of vision and visuomotor processing tests. For instance, one test asked the participants to watch at a computer screen with many dots moving in random directions and to determine whether the dots had a net upward or downward movement. In another test, children were asked whether the display contained either a circle or a square.
The level of children’s autistic traits was meaningfully tied to their performance in visual tasks, but the effect depended on their sex. Males with high autistic traits did worse on both object recognition and hand-eye coordination tests.
“In contrast, girls with high autistic traits had scores that were just as high as girls with low autistic traits, so object recognition was not meaningfully associated with autistic traits in girls,” Andrew Silva, a postdoctoral fellow at the University of Waterloo School of Optometry and Vision Science and a co-author of the study, told Healthnews.
The part of the visual system that handles object recognition is also connected to face recognition, recognizing nonverbal communication and facial expressions, the authors note.
However, girls showed the same association as males with the hand-eye coordination tests.
Silva says the findings raise a possibility that a difference in the visual processing system allows girls to better recognize their surroundings, nonverbal communication, faces, etc., making them more “invisible” than autistic boys.
"Having this kind of context could allow us to develop more sensitive ways of seeing and supporting people with neurodivergence earlier."Andrew Silva
He notes that it is unclear whether this visual process is preserved due to differences in how males and females are brought up in society or whether there is an inherent difference in the visual systems of neurodivergent children.
Flawed diagnostic tools
A 2022 study published in Biological Psychiatry followed a group of children at a higher risk of developing ASD, for example, having autistic siblings. The researchers found subtle differences in the structure of core symptoms of autism between girls and boys. When these differences were corrected and children were screened for ASD early, an equal number of girls and boys were identified as having concerns for autism.
Another study found that females are still disproportionately excluded from participation in autism research as a result of the Autism Diagnostic Observation Schedule (ADOS) test, which determines eligibility for studies. Originally developed using a largely male sample, the ADOS test does not consider differences between behavioral patterns in autistic men and women.
People with ASD may have problems with social communication and interaction and can engage in restricted or repetitive behaviors or interests. ASD may also pose challenges with earning, moving, or paying attention.
Social interaction characteristics related to ASD in children may include:
- Avoiding or not keeping eye contact.
- Not responding to the name or/and not showing facial expressions by 9 months of age.
- Using few or no gestures, like waving goodbye, by 12 months of age.
- Not noticing when others are hurt or upset by 24 months of age.
- Not noticing other children and joining them in play by 36 months of age.
Children with ASD may engage in restricted or repetitive behaviors or interests, such as:
- Repeating words or phrases over and over.
- Focusing on parts of objects.
- Getting upset by minor changes.
- Having obsessive interests.
- Flapping hands, rocking body, or spinning self in circles.
Some examples of other ASD-related characteristics are the following:
- Delayed language, movement, cognitive or learning skills.
- Hyperactive, impulsive, and/or inattentive behavior.
- Unusual eating and sleeping habits.
- Anxiety, stress, or excessive worry.
- Lack of fear or more fear than expected.
Addressing underdiagnosed autism in girls is crucial to give them timely support and interventions. The eye test could help to improve diagnosis, but further research is necessary.
- Journal of Autism and Developmental Disorders. Associations Between Autism Spectrum Quotient and Integration of Visual Stimuli in 9-year-old Children: Preliminary Evidence of Sex Differences.
- EurekAlert. Can a simple eye exam help diagnose autism?
- Autism Speaks. Autism Statistics and Facts.
- Biological Psychiatry. A Data-Driven Approach in an Unbiased Sample Reveals Equivalent Sex Ratio of Autism Spectrum Disorder–Associated Impairment in Early Childhood.
- Autism Research. Exclusion of females in autism research: Empirical evidence for a “leaky” recruitment-to-research pipeline.
Show all references
- Centers for Disease Control and Prevention. Signs and Symptoms of Autism Spectrum Disorder.