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Is Autism More Common In Boys

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Hypothesis Of Female Underdiagnosis

Study: Autism becoming more common in Utah 8-year-olds

The prevalence ratio is often cited as about 4 males for every 1 female diagnosed. Other research indicates that it closer to 3:1 or 2:1.

Some authors, clinicians and experts like Judith Gould, Tony Attwood, Lorna Wing and Christopher Gillberg have proposed that autism in females may be underdiagnosed due to better natural superficial social mimicry skills in females, partially different set of symptoms and less knowledge about autism in females among experts. In his preword to the book Aspergers and Girls, Attwood writes: These tentative explanations for the apparent underrepresentation of girls with Aspergers Syndrome have yet to be examined by objective research studies.

Specifically, Gould has discussed the idea that a pervasive developmental disorder called pathological demand avoidance, which is not officially included in diagnostic manuals may offer a glimpse about how autism in females may present in some cases.

Female phenotype

Some have suggested a differential phenotype for autistic women a female-specific manifestation of autistic strengths and difficulties, which fits imperfectly with current, male-based conceptualisations of autism.

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Boys Are Diagnosed With Autism For Every Girl

Demographics of Autism. Autism is most commonly diagnosed in boys. For every 1000 8 year-old boys, 24 are diagnosed with autism. For every 1000 8 year-old girls, 5 are diagnosed with autism. Interestingly, the diagnostic rate of autism varies significantly by state. In New Jersey, the CDC estimates that 24/1000 8 year olds are diagnosed with autism. Meanwhile, this number is only 5% in Alabama.

Generally, in the United States, there are 24 boys out of every 1000 8 year-olds who have autism.

Meanwhile, there are only five girls out of every 1000 8-year-old girls who have autism.

This shows a dramatic disparity that biology has yet to fully explain. Two key scientific studies provide some clues on possible reasons behind this.

Top Questions and Answers

Misconception : Autism Is The Same For Everyone

Autism is a spectrum each autistic person’s experience is unique.

And that means autistic people can have different support needs. In 2013, the American Psychiatric Association removed Asperger’s Syndrome from the diagnostic manual and changed the diagnosis to Autism Spectrum Disorder. Kayley Whalen with the Autistic Women and Nonbinary Network said Asperger’s was a label that referred to an autistic person who was considered to not have major barriers to functioning in society.

Some autistic people are nonverbal and need an augmentative and alternative communication device. But being nonverbal doesn’t mean they’re less capable of communicating. Brandi Thompson of Plano said her son, who is nonverbal, was grossly underestimated at school.

“In his own words, he was bored and angry, and they treated him like a baby,” Thompson said.

Thompson realized she herself was autistic when her son was diagnosed.

She said her mother worried she was autistic when she was a baby, but decided she was too smart to be autistic.

“People don’t get help unless they’re disruptive,” she said.

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What Autistic Women Have To Say

Many of the autistic women weve spoken to have talked about getting a late diagnosis, or have had difficulty getting the support they need.

As part of our Stories from the Spectrum series, we interviewed several women and girls, who shared their experiences with us.

“I feel autistic women are more likely to be described as anxious and an autism diagnosis overlooked, since it can challenge gender stereotypes.” Dr Camilla Pang

Sara Gibbs, autistic comedy writer, told us: “I think there is a lack of understanding of how autism can present in girls, who are often socialised differently.”

Charl Davies, autistic tattoo artist, said: “I find that being a female I am expected to behave a certain way to fit in socially which is why I have spent so much time masking.”

Dr Camilla Pang, autistic scientist and author, explained: “I feel autistic women are more likely to be described as anxious and an autism diagnosis overlooked, since it can challenge gender stereotypes.”

Dr Kate Fox, autistic poet and comedian, said:“I dont think theres an inherent difference between autistic men and women. What there is a difference in, is how society treats and socialises males and females.”

Gender Differences In Males And Females With Asd

Is Autism More Common in Boys? You

The above information provides an overview of just some of the differences found in the symptoms of autism spectrum disorder when comparing males and females.

In summary, males and females differ in the following ways when looking at the diagnosis of ASD:

  • males are diagnosed at a 4:1 ratio when compared to females
  • at a young age , females seem to have more motor deficits and lesson communication deficits when they are identified as meeting criteria for an ASD diagnosis at that time
  • as intelligence level increases, females are less likely to be diagnosed with ASD which may have to do with their ability to develop coping strategies to manage their life experiences despite having ASD
  • females may display different types of restrictive or repetitive behaviors as compared to males sometimes these behaviors are less noticeable to outside observers


Halladay, A.K., Bishop, S., Constantino, J.N. et al. Sex and gender differences in autism spectrum disorder: summarizing evidence gaps and identifying emerging areas of priority. Molecular Autism6, 36 doi:10.1186/s13229-015-0019-y

Matheis, M., Matson, J.L., Hong, E. et al. J Autism Dev Disord 49: 1219.

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What Does Autism Look Like In Girls

Although every child with autism is different, here are some common characteristics in girls with autism:

  • A special interest in animals, music, art, and literature
  • A strong imagination
  • A desire to arrange and organise objects
  • Not wanting to play cooperatively with female peers
  • A tendency to mimic others in social situations in order to blend in
  • An ability to hold their emotions in check at school, but be prone to meltdowns or explosive behaviour at home
  • Strong sensory sensitivities, especially to sounds and touch .

While girls with ASD are less likely than boys to also be diagnosed with ADHD and conduct problems, they are more vulnerable to internalising problems, such as anxiety, depression and eating disorders. As we learn more about autism in females, we appreciate just how important timely diagnosis, effective support, and understanding can be.

Differences In Motor Skills And Communication Skills

One study looked at the gender differences as related to symptoms of autism and developmental functioning. Those who were assessed in this study included children in the age range of 17 to 37 months who also met the criteria for a diagnosis of autism spectrum disorder .

In this study, no gender differences were found related to symptom severity. However, this study which examined toddlers with ASD, found that girls at this age range had more motor skill deficits but less communication skill deficits compared to boys.

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Autism Is Highly Driven By Genetics

Autism is highly driven by genetics. Autism is highly driven by genetics. Researchers estimate that 80% of variation in autism is due to inherited genetic factors. This varies by country.

Another more biological reason comes in the form of genetics.

As shown in the data below, autism is a highly heritable disorder. It is heavily driven by genetics.

A recent study estimated that 80% of autism variation is driven by genetics while 20% is driven by environmental factors such as upbringing and schools.

Genetic And Gender Differences Associated With Autism

Girls with autism are underdiagnosed and they’re different from boys

One theory about why autism appears to be more common in boys suggests that the disorder stems from one or more defective genes on the X chromosome. This genetic theory, proposed by D.H. Skuse, is based on the idea that boys, who have only one X chromosome, are more susceptible to autism because they do not have the protection of a second normal X chromosome as found in girls. Other genetic-based autism theories examine the possibility that boys are more susceptible to the disorder due to the mutations of several genes located on different non-sex chromosomes.

Some scientists and researchers speculate that the structure of the male brain, which tends to be wired in a technical rather than an emotional sense, is more conducive to the displaying of externalized autistic traits. Girls who have an autism spectrum disorder may be better able to conceal their condition due to a higher development of the brain centers that regulate concepts such as social awareness and the capacity to empathize with others.

Presently, the greater incidence of autism in boys cannot be fully explained by any conclusive research findings on the part of scientists or mental health professionals. It is hoped that continued studies on this topic will provide insight as to whether autism can be definitively linked to gender differences.

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Autism Has Always Been A Disorder For Boys

Hans Asperger, a German researcher who developed a theory of autism separately but in the same time period as Kanner noted in some of his initial observations that the symptoms themselves appeared to exhibit an extreme variant of male intelligence. In fact, one variant of the spectrum Asperger Syndrome got its name from this very researcher since he was believed to have suffered from it himself.

Today, as gender identity and equality have become loaded political questions, such a statement would immediately draw fire. The suggestion that either sex might be innately cognitively inferior to the othereven if only in particular realmsis subject to much debate today. And the conception of intelligence itself remains difficult to define unequivocally, leaving perceptions of it open to different interpretations.

Researchers have long known that at the most basic level, there are differences in the male and female brain. Male brains tend to be disproportionately larger than female brains. On standard IQ tests, men and women consistently test to the same average scorebut that is by design, since the tests are structured to elicit an average of 100 among the general population. When IQ tests were first being developed, girls routinely scored higher than boys up until around the age of 14.

What cant be easily accounted for is the fact that males have a far higher variation in scores: There are more men than women at the top of the scale and at the bottom.

Is There Really A Male Bias

The diagnosis of classic autism and Asperger Syndrome , known as Autism Spectrum Conditions , rests on difficulties in reciprocal social interaction and communication, alongside strongly repetitive behavior and unusually narrow interests . The prevalence of ASC is estimated to be 1% ,. A diagnosis of classic autism, unlike AS, also requires the presence of additional learning difficulties and language delay. ASC is neurobiological, evidenced by atypical brain development in structure and function . ASC is also genetic , though not without some interaction with environmental influences.

ASC is strongly biased towards males , with ratios of 41 for classic autism and as high as 111 in individuals with AS . The specific factors responsible for the higher male prevalence in ASC remain unclear. ASC is not the only neurodevelopmental condition more common among malesa greater prevalence in males versus females is also seen in Attention Deficit and Hyperactivity Disorder , dyslexia, conduct disorder , specific language impairment, Tourette Syndrome, and Learning Difficulties .

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The Fetal Testosterone Theory

Fetal androgens affect the brain: Evidence from animal and human studies.

Animal studies, especially in rodents, confirm that early exposure to androgens acts on the brain to produce sex differences in behavior, cognition, brain structure, and function . It is widely accepted that fT exposure also affects brain development and behavior in humans. Human males experience a surge in fT between weeks 8 to 24 of gestation , reaching almost pubertal levels. There is also a second surge soon after birth . Usually the levels remain high and then drop to barely detectable levels by 46 months , until the third surge at puberty. Whilst the third surge is understood to be controlling the onset of puberty, the function of first surge is believed to play a major role in brain masculinization.

While direct manipulation of hormones as has been conducted in animal studies is unquestionably unethical in human fetuses and infants, alternative research strategies include relating individual variation in amniotic fT exposure to later development , or studying people in whomfor medical reasonsthe sex hormones are higher or lower than expected for a person’s sex , and using proxy measures of fT exposure. Here we review evidence from studies of cognitive traits relevant to ASC and their relationship with amniotic fT.

Fetal androgens affect ASC traits: evidence from amniotic fluid testosterone.

What Are The Signs Of Autism

Why is Autism More Common in Boys?

Some of the most common signs of autism in children include:

  • Shows no interest in pretend play
  • Prefers to play alone and avoids eye contact
  • Shows little interest in others and their feelings
  • Delayed speech and language skills, including a notable regression or delay, starting from 18-24 months
  • Reacts in extreme ways to sensory stimuli involving smell, sound, taste
  • Is obsessive about specific toys, objects, or activities
  • Is unable to cope with changes to routine, may even react strongly to minor changes or upsets
  • May show little interest in or react negatively to physical contact
  • Is unable to read obvious social cues or understand appropriate behavior based on the environment
  • Self-stimulatory and repetitive behavior is common, including physical tics

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Misconception : Autism Only Impacts Boys

According to the Center for Disease Control, boys are 4.3 times more likely than girls to be diagnosed with autism.

Girls are diagnosed later, according to Dr. Kevin Pelphrey, a child psychologist who studies autism in girls. His research found that autism can manifest in different brain systems in girls than in boys. Autistic girls, he said, tend to have dysfunction in the parts of the brain that handle motor skills, executive function and emotional regulation.

“In boys, it’s much more what we kind of thought autism always was, which was dysfunction in brain systems involved in social communication and social development,” Pelphrey said.

Gender affecting the cause of autism is unusual. Pelphrey said in most medical conditions, the cause is the same, but the symptoms are different.

There isn’t a lot of research on autistic girls. Pelphrey said the lack of research means girls are misdiagnosed and miss out on early intervention.

The X Chromosome Theory

The X chromosome contains more genes expressed in the brain than the other chromosomes . In addition, more than 10% of people with learning difficulties show an X-linked pattern of inheritance , involving mutations in over 90 different X-linked genes ,. Individuals with X-linked learning difficulties may also have ASC, the best-known example being Fragile X Syndrome, where 46% of males and 16% of females carrying the full mutation also have ASC .

Girls with Turner Syndrome are at an increased risk for ASC, which could be the result of an X-linked recessive gene, but this is not clear-cut since XYY and XXYY males are also at increased risk . One study has also reported higher autistic traits scores , though this is not always seen .

Creswell and colleagues subsequently reported five cases of ASC from an unselected sample of 150 subjects with TS. All the cases were XmO . All of the cases in that report also had moderate to severe learning difficulties and low verbal IQ scores, despite the fact that intelligence is usually in the average range in TS. This raises the possibility that the kind of ASC observed was related to learning difficulties . Also, given that 77% of TS females are XmO, while only 23% are XpO , this means that one would expect to find ASC more often associated with XmO than with XpO.

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Why Are More Boys Diagnosed With Autism Than Girls Multiple Factors At Play And More Research Needed

Posted on Tuesday, 01 June 2021, in

Between four and five times as many boys as girls are diagnosed with ASD each year. The same has been more or less true ever since the first cases of autism were described in the 1940s. And while there have been considerable improvements in the development of support and understanding of the needs of autistic people, the ratio has remained relatively static.

Despite the remarkable consistency, no mechanism has been proven to definitively account for this difference. Various hypotheses exist. The well-known but much criticised, extreme male brain theory, suggests that exposure to high levels of testosterone during gestation primes fetal brains to be more male-like, enhancing tendencies such as spotting patterns in the world and thinking systematically while diminishing female-like traits, such as empathy and the ability to observe social cues.

Another popular theory is the female protective effect, which proposes that females are genetically more resistant to certain factors that increase the likelihood of autism in an individual.

Historically, the diagnostic measures have been based largely on a male perspective due to the stereotypical view of autism. If a girl doesn’t fit this profile, their symptoms can easily be misinterpreted as something else. As a result, many females with autism are misdiagnosed and miss out on the support they need.

New Clues Emerge About Why Autism Is More Common In Boys

Why Autism is more prevalent among boys in today’s world

Autism spectrum disorders are roughly five times more common in boys than girls, for reasons which have long eluded doctors and researchers.

Now, a new study lends support to the so-called female protective model, which suggests it takes more extreme genetic mutations to produce symptoms of autism or neurodevelopmental disorders in girls than in boys.

Females require more mutational hits to push them over into a state of autism, intellectual disability or developmental delay, Evan Eichler, a professor of genome sciences with the University of Washington and an author on the study, told The Huffington Post. The findings were published in the American Journal of Human Genetics on Thursday.

Eichler and colleagues analyzed DNA samples of more than 15,000 boys and girls with neurodevelopmental disorders, and just under 800 who had been diagnosed with an autism spectrum disorder.

They looked for what Eichler called really bad gene mutations, things like copy-number variants and single nucleotide variants .

Girls who had been diagnosed with neurodevelopmental disorders and autism spectrum disorder had more harmful mutations than boys. Therefore, the theory goes, girls brains may need more mutational hits to push them over into a state of autism, intellectual disability or developmental delay.

Eichler said that the new study does not solve anything, but he hopes the findings help fit one more piece in a complex puzzle.

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