A version of this article first appeared in iancommunity.org.
Autism primarily affects boys, right? Officially, boys outnumber girls with autism by four to one (and ten to one in “high-functioning” autism).1 In fact, almost everything we know about autism comes from studying boys. But now some scientists are making discoveries that challenge common assumptions about autism, girls and gender.
They began with questions that have dogged researchers for years. Why are so few girls diagnosed with autism? Are girls simply less susceptible? Does autism look different in girls, making it harder to detect or diagnose?
A growing number of studies suggest that girls with autism, particularly those without intellectual disability, may be hiding in plain sight. They appear to have less severe symptoms than boys and to be better able to mask their social challenges at school.2,3,4 Although that may sound like good news, it can have a downside. According to research by the Interactive Autism Network (another online autism research community) and others, girls with milder forms of autism are diagnosed later than boys, possibly delaying intervention.2,5,6,8 Some may not be diagnosed at all. And, particularly in the teen years, girls with autism appear to suffer anxiety and depression more commonly than either boys with autism spectrum disorder (ASD) or typically developing girls.
EXAMINING GENDER DIFFERENCES FROM AN EARLY AGE
Several researchers said they began studying girls after hearing firsthand about their struggles to get a diagnosis and find services for ASD.
Psychologist Rachel Hiller, now at the University of Bath in England, led two studies of gender differences in Australia.2,3 In one, her team surveyed parents or grandparents of 92 boys and 60 girls about their children’s behavior. All had autism but not intellectual disability. The result? Boys and girls with ASD look different as early as the preschool years, according to their caregivers.
Little girls were reported to be more likely than boys to mimic others in social situations and to want to fit in with other kids. “They often develop a way to camouflage their symptoms. Also, they tend to obsess over friendships and can develop them, or one or two close and like-minded allies,” says Robyn Young, an associate professor of psychology at Flinders University in Australia and a member of Hiller’s team.
Boys are more likely to withdraw and isolate themselves from others. In fact, the boys’ parents tended to be more worried about their sons’ isolation, while the girls’ parents reported more concerns about emotional outbursts such as meltdowns.2 A separate study, of children in the Simons Simplex Collection, added irritability and lethargy to the list of problems that affect girls more than boys with ASD.7
Girls control their emotions better at school, where they act far differently than they do at home, according to several studies of children with autism and average-range IQ.2,3,4 Teachers are much less likely to voice concerns about girls than boys.2 That is “possibly because boys are more disruptive,” Young said. Teachers appear to focus more of their attention on boys with autism, who reportedly struggle with hyperactivity and classroom behavior.4
Nonetheless, girls with autism are just as impaired, or more impaired, in their social and communication skills, according to some studies.4,7 Boys and girls have similar problems with understanding social situations. But some girls have an edge on boys when it comes to using gestures and maintaining a conversation.3
THE 4 O’CLOCK EXPLOSION: HOME VS. SCHOOL BEHAVIOR IN AUTISM
“For many kids with ASD — but especially girls — parents say that their child manages to hold it together at school but then comes home and has to release the pressure built up during a day of pretending to be someone else. They call it the 4 o’clock explosion,” says researcher William Mandy, senior lecturer at University College London.
Interestingly, teachers may miss more autistic symptoms in girls than clinicians or parents do. In one of Hiller’s studies, teachers reported no concerns with conversational skills in half the girls with autism; clinicians, on the other hand, had no such concerns in only 17 percent of those girls.3
It’s not clear why teachers, clinicians and parents see girls with autism so differently, from the preschool years on. Are girls better able to blend in at school, while falling apart at home?
“In that sense, the finding that girls are especially likely to fly under the radar at school does fit with my clinical experience, and with the reports of quite a few parents I have spoken to,” Dr. Mandy said in an email interview.
As a group, girls are more likely to control their behavior in public; they are less likely to have public meltdowns, make socially inappropriate comments or speak too loudly.3 That is, they may be hiding their autism.
Liane Holliday Willey described her efforts to cope with ASD in her aptly titled autobiography Pretending to Be Normal: Living with Asperger’s Syndrome. In it, she records her exhausting attempts to fit into the “neurotypical” world, with its puzzling social rules and conventions.
Pretending — or trying to blend in — at school sounds like a coping skill, but it also may hinder diagnosis. Teachers often make referrals for educational or disability testing for their students. Is failing to attract attention in the early school years one way girls go undiagnosed and untreated?2 How can a family doctor decide whether to test for autism if teachers and parents have vastly different impressions of a girl’s behavior?3
Even when parents or teachers do refer a girl for testing, do her symptoms align with those commonly found in boys with autism? If they don’t, will those diagnostic tests and descriptions of autism — developed with boys in mind — fail to detect the disorder in some girls?
Some parents of girls say their daughters’ symptoms differed from typical (male) autism, making it hard to convince people of a problem.
“EVERYONE SAID, ‘SHE’S FINE.’”
Leslie knew something was different about her 2-year-old daughter, Ann. The girl wouldn’t respond to her name or make eye contact, but her outward behavior did not seem very unusual to others. “Everyone said, ‘She’s fine. There’s nothing wrong with her.’ But I was very persistent.”
She enrolled Ann in the preschool that her brother had attended and asked the teacher to keep an eye out for developmental problems. By January of that school year, the teacher told her, “I absolutely agree with you,” Leslie recalls. Her daughter didn’t line up toys, as many boys with autism do. Instead, “she played with them in a markedly different way than other children. She also did not interact with other children in an age-appropriate way,” says Leslie, who participated in the Simons Simplex Collection. (She asked that their real names not be used, to protect her daughter’s privacy.)
With the teacher’s observations in hand, Leslie took her daughter for testing, which led to an ASD diagnosis. “I knew how a typically developing child should behave since I had an older son; my daughter’s behaviors were different. Because I was very insistent on pursuing answers, I was able to get her diagnosed relatively early,” she says.
ARE GIRLS WITH AUTISM LESS “OBSESSED” THAN BOYS?
Research backs up the observations of parents like Leslie. Some girls with autism really do have less obvious autistic symptoms than boys with the same diagnosis.
The list of common autistic mannerisms — which experts call “repetitive and restricted behaviors” — comes primarily from studying boys with autism. These behaviors include lining up toys, a fascination with spinning wheels or parts of objects and obsessions with trains, motors, video games or mechanical objects. But now researchers say girls with autism have either milder repetitive behaviors4,7 or simply different ones.2,3
For one thing, girls with ASD are less likely than boys to line up or sort things.2,3,4 One study of children in the Simons Simplex Collection found lower levels of obsessive interests in girls than in boys with ASD.7
A study by the Interactive Autism Network also found that the girls in its large U.S.-based registry have milder autistic mannerisms than the boys.8 “This and other studies are suggesting that girls with ASD … differ from males in key symptoms and behaviors, particularly around social interactions,” says IAN Director Paul H. Lipkin. “We must consider whether the girls are not only being recognized later but also may be underidentified due to less pronounced symptoms.”
Most studies of autism in girls include only girls who have been diagnosed with autism, but one large study in the U.K. looked at girls with autistic symptoms but no ASD diagnosis. It found that girls with high levels of autistic traits but without behavior or learning problems may be missed by the tools used to diagnose ASD. That may be due to a gender bias in diagnosis or because girls are able to adapt better to their condition than the boys, the researchers concluded.9
CAN A SHELL COLLECTION OR AN INTEREST IN FASHION BE A SIGN OF FEMALE AUTISM?
Some researchers wonder if girls’ obsessions and rituals might not show up on autism screenings or be flagged by parents because they seem neither odd nor unmanageable.
Hiller says that girls are more likely than boys to have “seemingly random obsessional interests (e.g., collecting shells, pencils) from the preschool years right through to adolescence. Perhaps these interests are harder for clinicians and family doctors to identify when the girl is young, as they are more in line with the interests of typically developing girls. However, as the girl grows older, it may become more apparent that the interest is very different from her same-aged peers. It is also possible that in the preschool years, girls’ interests are less intense or less disruptive on family life, and thus less likely to be identified as problematic.”
Mandy says girls with autism may have the same interests as other girls — but with a twist. “For example, I have met quite a few females with ASD with very, very strong interest in fashion, hair and appearance in general. Nothing unusual about the topic of interest, but in these instances it was pursued with an autistic intensity.”
American psychiatrists now require someone to have some repetitive behaviors and obsessions in order to receive a diagnosis of autism spectrum disorder. Researchers have wondered whether girls and women will find it harder to get an ASD diagnosis under that new criterion.7
If diagnostic tests — and doctors — sharpened their focus on female autism, would the gender ratio be different? The jury is out.
Mandy says, “I do believe that males are more susceptible to ASD than females, but I think we exaggerate the extent of this gender difference, especially amongst people with normal-range IQ and fluent speech. If you asked me to take a bet on the true gender ratio in ASD, I would say it is two males to every female. And I think that one reason why [autism] clinics tend to find a higher male-to-female ratio is that some females never come to the attention of ASD services, because they mask their autistic difficulties more effectively than males.”
If girls can learn to mask their symptoms, could boys do so as well? “Studying how girls with ASD camouflage their difficulties will certainly teach us about boys too. Lots of boys are camouflaging too. Are they doing it differently? Less well, or as well? Less often? All these questions remain to be answered scientifically,” Mandy says.
Is there a cost to all the pretending? A number of studies show that girls with ASD tend to experience depression and anxiety more often than either boys with ASD10,11 or typically developing girls,12 although no one knows why.
Mandy’s research shows that some of the differences between girls and boys with autism — such as those related to depression and anxiety — mirror gender differences in the general population.4
“When we see gender differences on the autism spectrum, are these similar to gender differences in the rest of the population? To answer this, we need to include male and female non-ASD control groups in our studies of ASD gender differences,” Mandy says.
And that is a matter for future research.
Interested in joining SPARK? Here’s what you should know.
- Fombonne, E. (2009). Epidemiology of pervasive developmental disorders. Pediatric research, 65:591-598. View abstract.
- Hiller, R.M., Young, R.L., & Weber, N. (2015). Sex differences in pre-diagnosis concerns for children later diagnosed with autism spectrum disorder. Autism, Feb 25. View abstract.
- Hiller, R.M., Young, R.L., & Weber, N. (2014). Sex differences in autism spectrum disorder based on DSM-5 criteria: evidence from clinician and teacher reporting. Journal of Abnormal Child Psychology, 42:1381-1393. View abstract.
- Mandy, W., Chilvers, R., Chowdhury, U., Salter, G., Seigal, A., & Skuse, D. (2012). Sex differences in autism spectrum disorder: evidence from a large sample of children and adolescents. Journal of autism and developmental disorders, 42(7), 1304-1313. View abstract.
- Begeer, S., Mandell, D., Wijnker-Holmes, B., et al. (2013). Sex differences in the timing of identification among children and adults with autism spectrum disorders. Journal of autism and developmental disorders, 43, 1151-1156. View abstract.
- Rivet, T.F., & Matson, J.L. (2011). Review of gender differences in core symptomatology in autism spectrum disorders. Research in autism spectrum disorders, 5(3), 957-976. View article.
- Frazier, T.W., Georgiades, S., Bishop, S.L., & Hardan, A.Y. (2013). Behavioral and cognitive characteristics of females and males with autism in the Simons Simplex Collection. Journal of the American Academy of Child and Adolescent Psychiatry, 53(3), 329-340. View abstract.
- Chen, B., Marvin, A., & Lipkin, P.H. (2015). Gender differences in diagnosis and social characteristics of children with autism from a US registry,” presentation at the 2015 Pediatric Academic Societies meeting April 28.
- Dworzynski, K., Ronald, A., Bolton, P., & Happé, F. (2012). How different are girls and boys above and below the diagnostic threshold for autism spectrum disorders? Journal of the American Academy of Child and Adolescent Psychiatry, 51(8), 788-797. View abstract.
- Hartley, S.L., & Sikora, D.M. (2009). Sex differences in autism spectrum disorder: an examination of developmental functioning, autistic symptoms, and coexisting behavior problems in toddlers. Journal of autism and developmental disorders, 39(12), 1715-1722. View abstract.
- Gabriels, R.L., & Hill, D.E. (2007). Growing up with autism: working with school-age children and adolescents. New York: The Guilford Press, 11-12.
- Solomon, M., Miller, M., Taylor, S.L., Hinshaw, S.P., & Carter, C.S. (2012). Autism symptoms and internalizing psychopathology in girls and boys with autism spectrum disorders. Journal of autism and developmental disorders, 42(1), 48-59. View abstract.