How Autism Differs for Girls & Boys (Science & Statistics)

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The ratio of boys to girls with autism is lopsided. For every one girl with autism, three boys qualify for the diagnosis. 

In 2017, when this statistic was released, researchers celebrated. Prior studies suggested the gap was even wider, and experts attributed that to misdiagnosis. Girls were slipping through the cracks, they told us, and girls weren't getting the help they needed. The more girls with a diagnosis, the reasoning goes, the fewer overlooked cases.

Other researchers aren't so sure. 

Some experts say that the science shows that boys have autism vulnerabilities girls don't share. Others say we may never identify all the girls with autism, as the testing tools we use are made specifically for boys. 

The more we know about how autism differs in boys and girls, the more we can revise our tests, our therapies, and our strategies. Perhaps, in time, we can get girls with autism the help they deserve without minimizing the very real risks boys face.

Are Genes to Blame? 

Physical differences between boys and girls are more than skin deep. The science says that a female brain is structurally different from a male brain, and her chromosomal makeup is different too. Those two factors could offer protections. 

The cortex, the outer layer of the brain, is full of nerves responsible for:

  • Memory
  • Language
  • Thinking

Women have thicker cortices, when compared to men. A 2017 study suggests that a thin cortex, regardless of gender, raises autism risks

If women have a naturally thicker cortex, the thinking goes, they have built-in protection from autism. They have a bit of tissue to spare, so the disease might be in a mild form for them, if it appears at all. 

Women also have a different hereditary makeup compared to men. Women have two X-chromosomes, while males have only one. Researchers found a mutation on the X-chromosome associated with autism. Since women have two, a faulty version could be overruled by the cleaner part of the pair, and that provides enhanced protection.

Studies like this are preliminary. Researchers need to do more work with:

  • Cells. Association doesn't prove cause. Studies that pinpoint exactly how these changes either lead to or protect against risk are required, and they are performed with cell.

  • Controls. Studies involving neurotypical people are critical, as researchers need a control set to compare to.

  • Study length. Short studies with small data sets aren't as valuable as long studies that track information over an extended period of time.

Despite the need for more research, early studies hint at biological differences that could explain diagnosis disparities.

Are Expectations the Cause? 

We reinforce ideas of gender with our expectations of boys and girls. Some researchers and experts believe that our interpretation of how girls and boys should behave can hide some autism symptoms and amplify others. 

In 2019, researchers examined this issue. Their study set included:

  • Parents. The researchers examined adults raising children with autism spectrum disorder.
  • Twins. More than 30,000 children were included.
  • Established data. They used published studies as controls.

The researchers found that boys with autism had higher autism-specific scores than their female counterparts. However, the girls with autism had much different test results than neurotypical females.

In other words, the boys scored high on autism metrics. But the girls were very different than their peers, even when their autism scores were low. 

Differences become prompts for bullying. Research like this suggests that girls with autism might get missed in standard tests, even when their peers can identify that something is amiss. Do we perpetuate that problem by allowing girls to bully one another? 

Other research centers on bias. Do we assume more boys will have autism, so we screen them more frequently than girls?

In one study, researchers followed children from infancy. Periodically, the children had autism tests, and the difference between boys and girls persisted. Some say the tests are to blame.

Autism screening tests might look for symptoms that are traditionally male, such as:

  • Hyperactivity or impulsivity.
  • Conduct difficulties.
  • Externalizing problems (via yelling, for example) rather than keeping them inside.
  • Poor social skills or peer shunning.

Perhaps there's a specific female version of autism, and it merits a separate screening tool, experts say. If girls are societally expected to be quiet, calm, obedient, and friendly, that pressure could drive them to hide their autism tendencies or morph them into a new shape.

Do Girls Mask Autism Symptoms?

When people push their symptoms down to avoid detection, it's called masking. Some researchers believe that girls with autism are adept at hiding their troubles, even though they persist. That could keep them from getting the help they need.

Experts say masking can involve:

  • Interests. Autism sparks an obsessive interest in a limited number of topics. For boys, maps, mathematical equations, or other adult-seeming topics could be the target. Girls, on the other hand, might like things that seem gender-appropriate, like unicorns or horses.
  • Social skills. Girls with autism tend to make more eye contact and smile more frequently than boys with autism do.
  • Order. Routines and structure can be comforting for people with autism. In girls, this can be overlooked as stereotypical female cleanliness.
  • Imitation. Some girls with autism know that there's something unusual about how they interact with the world. They learn to just copy their peers as much as possible.

Girls adept at masking pay the price. Researchers say they have higher depression and anxiety levels in adolescence than their peers. If they never get the right diagnosis, they could be treated for conditions they don't have with poor results. 

For example, people with autism often have restricted eating habits. Girls can be misdiagnosed with anorexia, and they could get pushed into programs that address only disordered eating. Until the autism component of the eating is addressed, these girls may never approach food in the way their therapists hope they will.

Spotting Autism in Boys & Girls

Research about autism is ongoing. Statistics and our overall understanding morph as we learn more. For example, while scientists can spot brain changes associated with autism in babies in utero, they can't diagnose autism with a brain scan. Doctors rely on interviews with parents and children to make an official diagnosis of autism spectrum disorder. 

Doctors can diagnose autism in children younger than 2 years, experts say. The disorder can be reliably diagnosed between 18 and 24 months, though on average, children are diagnosed at 3 years old. Your doctor will ask about milestones, such as:

  • Crawling.
  • Talking.
  • Smiling for the first time.

Doctors may also look over notes from family members, babysitters, and other caregivers. Older children may have teachers who provide input too.

For a girl, autism symptoms include:

  • A deep interest in animals, literature, music, or art.
  • A rich imaginary life.
  • A desire for control, both in her environment and her relationships.
  • Strong mimicry skills.
  • Enhanced sense of sound and touch.
  • Meltdowns at home but controlled behavior at school.

Boys may share some of these symptoms, but they may also have at-school conduct problems, reduced verbal skills, an unwillingness to make eye contact, and a need for unusual vocal sounds. 

If you spot symptoms in your child that seem unusual or amiss, talk with your doctor. If your doctor doesn't agree with your assessment, ask for a second opinion from a psychiatric or mental health professional. Autism can be quite subtle in some children, and it's not unusual for parents to advocate for months before a diagnosis is given. 

Diagnosis is critical, as it connects your child with therapies that can help. Applied behavior analysis (ABA) therapy, for example, could help your child to both understand autism and learn how to build skills that are limited by the condition.

ABA therapy can be intense, which makes the results strong and lasting, but professionals know how to make it fun and engaging for children. It could be the solution your family has been looking for.