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Autism in females: the gender split

"Males are at least two times more likely than females to be diagnosed with autism spectrum disorders (ASDs)” says Dr William Davies, Senior Lecturer at Cardiff University's MRC Centre. But why?

Dr Davies says that “this striking bias is due to a complex combination of social factors (ascertainment and diagnostic biases) and biological factors.” In this post, we will examine the social and biological factors affecting diagnoses in females with ASDs and highlight where individuals can find support.

A clouded history

When Hans Asperger first defined autistic psychopathy, it was thought only to affect boys. Although we now know this to be untrue, it has been argued that stereotypes held by doctors themselves mean that many females remain undiagnosed with autism; for example, on the basis that they engage in conversation and make plenty of eye contact.

However, Dr Davies contends that it is the methods for diagnosing Autism Spectrum Disorders (ASDs) that might be to blame. “The diagnostic criteria for ASDs were originally specified on the basis of how cohorts comprising mainly male cases behaved, and so inevitably a bias in diagnostic prevalence may be expected.” In other words, the methods for diagnosing ASDs are not wholly applicable to girls.

Masking the truth

Why are girls so difficult to diagnose? Generally, girls do not exhibit as many repetitive behaviours as boys, such as hand flapping and dystonic posture of hands and fingers. Girls also have a more even profile of skills than boys. Although girls on the spectrum are unable initiate social play, they are able to mask their symptoms by imitating their peers. They exhibit behaviours in which they appear to be interacting with peers effectively, whilst they do not understand the full subtext of what is going on.

This constant ‘role play’ can be the source of much frustration for girls; often resulting in ‘meltdowns’ where individuals cry, vomit or bang their head against the wall.

Girls with autism have very similar interests to their peers, which makes them seem like any other female of that age. What differentiates them however, is that these interests and hobbies can become obsessions. This kind of repetitive behaviour is on the spectrum of autism and is a vital indicator of the disorder. Girls with autism may also get into arguments with teachers at school. This is due to a failure to understand social hierarchy and how to interact with people of a different status.

Autism can coexist with other mental health disorders, which can make autism very difficult to diagnose; anxiety, paranoia and personality disorders, for example. As such, many psychologists agree that unless the methods for diagnosing autism are adapted to suit females, that this will continue and many women will remain undiagnosed well into their adult life.

It’s in the genes

There is evidence to suggest that boys are just more likely to develop autism than girls, however. Dr Davies highlights a number of reasons why this might be the case; and they’re all to do with genes. Hold onto your hats, ladies and gentleman…

These explanations are based on the understanding that girls have two X chromosomes (one from each parent) whereas boys have an X (from their mother) and a Y (from their father). This is otherwise known as ‘sex determination’, and presents a number of biological differences which might affect the chances of developing autism:

Firstly, boys produce twice as much testosterone in the womb as females do, but growing research suggests that this is even higher in autistic males. But although prenatal exposure to testosterone has been linked to the development of ASDs, there is not enough evidence to suggest that it is a predictor of autism.

Another factor is related to genetic mutations on the cognition rich X chromosome. Boys only get one X chromosome, and if genetic mutations do occur, then they cannot be masked by an additional X chromosome.

Other studies suggest that X chromosomes inherited from the father can protect against developing ASDs. Boys only get one X chromosome from their mother, so might be more at risk of developing an ASD.

Support for females with autism

An illustration from The Girl with the Curly Hair by Alis Rowe

If you are an individual, parent or carer affected by autism, there are a number of helpful resources available to you:

The Girl with the Curly Hair was written by Alis Rowe, a female who was diagnosed with autism at age 22. It brings together a mix of pictures and wordplay which conveys experience of living with an ASD. The book forms part of the ‘Curly Hair Project’ which aims to “improve understanding and communication between women and girls on the autism spectrum, and their loved ones.”  Readers report that this book is able to accurately convey what it is like to live with an ASD, rather than the common clinical explanation for autism.

More information on issues relating to autism and gender can be found via The National Autistic Society website.

With many thanks to Dr William Davies, Senior Neuroscience Lecturer at Cardiff University.

Julia Pearce

Mae Julia yn Swyddog Cyfathrebu yn yr Is-adran Meddygaeth Seicolegol a Niwrowyddoniaeth Glinigol ym Mhrifysgol Caerdydd.

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