Spend a few minutes around a group of late-diagnosed autistic folks, and you’ll quickly pick up on a pattern.
Most of them will be women, and most will be able to recount dozens of signs, traits, and symptoms that, in retrospect, they feel should have resulted in a diagnosis much earlier. (Some will say things like, “Well, my brother’s was just so much more obvious; I guess nobody noticed mine.”)
Now a new study seems to affirm what they’ve been saying: girls have autism at rates approximately equivalent to boys, but their diagnoses come, on average, about 3 years later.
Autism Diagnosis Has Increased Over Time, Regardless Of Gender
A study followed every child whose birth was registered in Sweden between 1985 and 2020, and their routine healthcare afterward, including regular assessments of motor skills, cognitive development, and social skills. Those who were, at any point, referred for an assessment of autism spectrum disorder had that assessment and its outcome documented.
Autism diagnoses have increased overall, with a shift in our understanding of the diagnosis. Diagnostic criteria shifted in the mid-1990s and again in the 2010s, and with each shift came an increase in the number of individuals whose traits met the criteria.
This particular study, published in the BMJ, found that diagnoses became 10 times as common over the 35-year period covered.
That doesn’t mean that the traits that merit an autism diagnosis are necessarily on the rise, only that the way autism is diagnosed has changed, so that medical science is recognizing more individuals as falling into the category.
Boys Often Get Diagnosed First
Older data, such as a meta-analysis published in 2016 in the Journal of the American Academy of Child and Adolescent Psychiatry, already showed a shift in the gender imbalance.
At that time, the researchers reported that, among children, the ratio of boys to girls meeting the diagnostic criteria was closer to 3 boys per girl than 4 boys per girl, as previously postulated, and acknowledged that girls were being overlooked.
“There appears to be a diagnostic gender bias, meaning that girls who meet criteria for ASD are at disproportionate risk of not receiving a clinical diagnosis.”
Now the newer data shows that, in fact, the ratio is much closer to 1:1, over time, but boys still tend to get diagnosed first.
For instance, between 2020 and 2022, boys under age 5 were about 4 times as likely as girls to be diagnosed, but the rate of diagnosis for girls between ages 15 and 19 was about the same as for boys between the ages of 10 and 14 — what the researchers describe as “catching up.”
Why Do Girls Get Overlooked In Diagnostics?
There are a few theories about why girls may be skipped over for diagnosis.
One theory is that social pressure may compel girls to learn to better mask their symptoms. The Recovery Centre (TRC) describes, for instance, that girls are often socially expected to be quieter and more empathetic, and adds, “it makes sense that autistic girls may go to greater efforts to match these societal expectations, and mask any traits that may differ from what society expects of them,” and that they may express difficulties differently.
“While autistic boys are more likely to show externalising behaviours such as hyperactivity or conduct problems, autistic girls may be more prone to internalising their difficulties (similarly to non-autistic girls). This can lead to autism being missed in girls, as internalising behaviours are not as easily observable from the outside.”
However, the most well-documented factor is simple bias in diagnostic and research practices. While there isn’t really such a thing as “girl autism” and “boy autism,” there can be traits that are more likely to present differently by gender, and traditionally, autism presentation in boys has gotten more attention and study, and is more recognized by doctors, teachers, and even parents.
One study published in Autism Research in 2020 actually asked teachers to identify the autistic kids from a series of fictional vignettes, and found that not only were teachers less likely to miss autistic traits that are more common in girls, they were also more likely to miss a given trait in a girl vignette, even if they identified it in a boy vignette.
What Should Parents Take From This?
Autism has a genetic component, so if you have a son or sons who are diagnosed, be aware that your daughter(s) may also be autistic, and may fly under the radar.
If you do feel that your daughter is showing signs of autism, speak to her doctor, even if her teachers and other adults in her life aren’t raising concerns. If you feel brushed off, seek a second opinion, and always be aware that you have the right to seek an evaluation.
Watch for traits that can be overlooked in girls. For instance, they may channel stimming into socially acceptable behaviors such as applying nail polish, brushing their hair, or dancing. Or, when they form a deep interest in a specialized topic, it may be easier to overlook if it’s a “typical” interest stereotyped to girls, like celebrities, makeup, or horses. They may also hide social struggles by scripting conversations and mirroring peers, or social difficulties may be dismissed as merely shyness.
If you’re not sure, talk to your daughter and see how she feels.