Study: Autism in Girls May Be Just as Common as in Boys

Takeaways

• The long-held belief that autism is four times more common in boys than in girls may be outdated. A large-scale Swedish study suggests autism may be just as common in girls as in boys, especially when looking at diagnoses over time.
• Girls tend to be diagnosed much later than boys, leading to a “catch-up effect” in adolescence and young adulthood. Researchers found a 3:1 boy-to-girl ratio for diagnosis in early childhood, which drops to nearly 1:1 by age 20.
• Reasons for later diagnosis in girls include better communication skills and “masking” behaviors. Diagnostic tools may also be gender-biased. Later diagnoses means girls may miss out on the benefits of early interventions, potentially leading to anxiety and other mental health issues.

Autism spectrum disorder (ASD) is a developmental disorder marked by social and communication difficulties and restricted or repetitive behaviors, long thought to affect more boys than girls. The fifth edition of the Diagnostic and Statistical Manual for Mental Disorders states that for every four boys in the United States diagnosed with autism, one girl is diagnosed.

New autism research challenges this conclusion. The long-accepted gender difference in autism rates may in fact be much smaller, or nonexistent, when looking at diagnoses of autism in females and males over time.

A Swedish study published earlier this month suggests that autism may be just as prevalent among girls and boys in Sweden. The researchers examined data on 3 million people born in Sweden between 1985 and 2020 and diagnoses of autism recorded in the Swedish national patient register from 1987 to 2022 to investigate how the male to female ratio changed over time.

Main Findings

The study confirmed the established finding that autism diagnoses are increasing, highlighting a tenfold increase from the mid-1980s to 2022. Yet, while autism diagnoses are on the rise, the gender gap appears to be closing.

The study found a strong gender difference in early childhood diagnoses, with three boys diagnosed for every one girl under age 10.

In adolescence and young adulthood, however, diagnoses in girls had increased during what the researchers called the “catch-up effect,” dropping to a 2:1 ratio. By the time they reached age 20, the total number of females diagnosed with autism was nearly equal to the number of males diagnosed with autism.

According to the researchers, this finding highlights a need to explore why girls receive diagnoses of ASD later than boys.

Future research may also need to explore whether autism is as prevalent in girls in other countries.

Why Are Girls Diagnosed Later?

This study suggests that autism could affect girls and boys at similar rates, but girls have generally been diagnosed later than boys. Boys may receive a diagnosis earlier in life for several reasons. For example, the researchers cite past studies positing that girls tend to have better communication skills and engage in more masking behaviors to conceal their autism.

Caregivers and teachers may also be more likely to expect a boy to have autism, leading to an earlier diagnosis. Meanwhile, a girl’s symptoms of autism might be attributed to mental health issues or low self-esteem, which can lead to a misdiagnosis.

A related article suggests that girls may exhibit fewer repetitive behaviors or hyper-focused special interests than boys. In turn, it and other studies raise the possibility that the tools used to diagnose autism may be gender-biased.

Resources for Girls and Women With Autism

Children who receive an autism diagnosis early in childhood may benefit greatly from certain types of interventions, such as behavioral, speech and language, and physical therapies. These interventions may help them manage repetitive behaviors, navigate social situations, improve motor skills, and succeed in school, leading to better outcomes. A diagnosis can also provide children with a sense of understanding about themselves and the challenges they face.

The recent finding that autism is just as prevalent among boys and girls in Sweden highlights the need for more timely diagnoses and greater access to early interventions for girls. Otherwise, many girls with autism could go undiagnosed until adolescence or adulthood. Others could remain undiagnosed.

According to the Child Mind Institute, undiagnosed girls can develop anxiety, depression, and low-self esteem. Because of difficulties understanding social cues, they may also be more vulnerable to bullying and predators.

Resources specifically offering support to females with autism and their families include the Autistic Girls Network and Autistic Women & Nonbinary Network. The Center for Autism and Related Disabilities at the University of South Florida and the Autism Empowerment website also feature online content specific to women and girls with autism.

Parents, caregivers, and others should be aware that signs of autism in girls often differ from those in boys. Earlier evaluation and diagnosis for girls who may have autism is crucial, as they can significantly improve access to necessary supports, services, and accommodations for academic and social success, leading to better long-term mental health outcomes.

If parents suspect their child may have autism, they should consult their pediatrician and seek evaluation from a child psychologist or other professional, and pursue a second opinion if their concerns are dismissed. A diagnosis is the critical first step toward accessing essential early interventions and support.

Additional Reading

• Supplemental Security Income (SSI) for Children With Autism
• Lifetime Money Management for Children With Disabilities