The classic observation that males are around three times as likely as females to be diagnosed with autism may be at least partly due to implicit bias associating males with autistic traits, and against recognising autism in females, according to a new analysis from psychologists at Edge Hill University in Liverpool.
The researchers said that there was a predisposition to associate males with traits typically recognized as autistic, whereas stereotypically 'female' behaviours — such as heightened emotional expression and better social communication — often "stand in stark contrast".
"This implicit association is consistent with a higher male-to-female autism ratio," they said, as well as with "evidence that autistic females are more likely to remain undiagnosed or be diagnosed much later". Females have a higher average age of diagnosis and are more likely to be diagnosed in adulthood rather than childhood.
Lack of Understanding and Recognition of Female Autism
The team suggested that these discrepancies were partly founded on a lack of understanding and recognition of the female autistic phenotype.
To assess the scope of this bias, the study, published in PLoS ONE, sampled 300 subjects from the general population recruited through both online research and social media platforms. Among the participants, 14 had been given a medical diagnosis of autism.
Subjects completed an Implicit Association Test (IAT) along with an Autism Quotient (AQ) to assess explicit associations. The IAT recorded reaction times when categorising male or female names with autistic traits. Results showed a significant association between males and autistic traits. The AQ, assessing autistic characteristics within a series of male or female vignettes, also revealed specific items perceived as explicitly male traits, while only reverse-scored items were perceived as female.
Gender bias "may have a detrimental effect on the diagnosis rate of females and have profound effects on their wellbeing", the researchers said. Females are better at camouflaging their autistic traits than males, who in turn experience less pressure to mask symptoms, whereas females may be more likely to do so to try to 'fit in'.
Hence autistic females may be less likely to receive clinical support, even though "early intervention has many benefits, including more significant gains in communication and wellbeing" – thus autistic girls may be missing out.
"Another consequence of gendered stereotypes about autism is that they fuel common misconceptions of autism within the general population" and may strengthen "stigmas surrounding autism", the team said.
Overlap Between Gender Dysphoria and Autism
Furthermore the "heavily gendered view of autism" could influence the development of sexual identity, according to the researchers. Not only are autism and gender dysphoria both undergoing rapid and significant increases, but also there is a significant overlap between them. Research at the University of Cambridge has shown that people who do not identify with their birth sex have three to six times the rate of autism as others, while conversely, autistic people are more likely than neurotypical people to say they are gender diverse.
The researchers noted that gender dysphoric autistic participants in their sample had expressed that "gender-loaded stereotypes" surrounding autism "complicated" their understanding of their gender.
The "Extreme Male Brain" Theory of Autism
In attempting to explain the gender bias, the researchers said that one specific theory that "particularly perpetuates male autism stereotypes" was the "extreme male brain" theory, which suggests that due to their systemising nature and hindered emotional responses, autistic people are an example of a "hyper-masculinized" group of individuals, irrespective of gender.
This has caused "a lack of sensitivity towards the symptomology presented by autistic females", they said, as current diagnostic tools were "geared towards the male autism phenotype". They added: "Gender bias has likely filtered into academic research," with a sampling bias that favours male over female participants.
They concluded that their study "provides further evidence that the general public holds gendered views of autism", and that "current popular perceptions of autism are conflated with male rather than female stereotypes". They recommended replicating their research with autism specialists to understand how this bias might extend to professionals.
Asked to comment by Medscape News UK, Dr Peter Carpenter, chair of the Royal College of Psychiatrists' Neurodevelopmental Special Interest Group, said: "The College is keen to ensure all clinicians diagnosing autism are able to do so using the internationally recognised classifications that define autism as a neurodevelopmental disorder."
He said that clinicians should consider the role of gender as well as age, ability level, life experiences, and co-occurring mental health conditions in order to make a diagnosis. The College plans to publish a position statement on autism, covering early and accurate diagnosis, later this year.
Ellie Brownlie, evidence and research officer at the National Autistic Society, told Medscape News UK: "This research reflects what autistic people, our charity and other researchers already know – that society still associates autism with perceived masculinity, and that presumptions about a person's gender have an impact on whether others think they may be autistic.
"This research adds to our growing understanding of the impact of gender presentation on identifying autism. But more needs to be done to ensure that society can recognise and accept autistic women and girls, non-binary and transgender people, as well as autistic men and boys. Gender should never be a barrier to getting a diagnosis and the right support."