You might have heard that for every female diagnosed with autism there are roughly three to four males (Fombonne, 2009; Loomes et al., 2017).

But this ratio changes when you consider the person’s language, cognitive abilities, and even their age. The ratio of males to females where there is a co-occurring intellectual disability has been reported at around 1.5:1 (Yeargin-Allsopp et al., 2003), for those without, around 10:1 (Fombonne, 2009), and by adulthood, about 1.8:1 (Rutherford et al., 2016). This pattern tells a two-part story. Firstly, biologically, autism might not affect males and females equally (Ecker et al., 2017). Secondly, autistic girls without co-occurring intellectual disability are being missed (Dworzynski et al., 2012), only to be diagnosed later if at all (Begeer et al., 2013; Loomes et al., 2017).

So, what does autism look like in girls and women? The pattern of behaviours seen in autistic girls and women is known as the ‘female autism phenotype’ (Kopp & Gillberg, 1992). Girls and women might be more inclined, better able, or are taught from a young age to mask their autism (Hull et al., 2019; Lai et al., 2015). They tend to desire friendships and develop strategies like watching and impersonating other girls (Tierney et al., 2016). They can be socially successful, though this becomes more difficult with age, as the complexity of the social world increases and the effort of masking (see section on Masking later in this article) comes at a cost to their wellbeing and sense of identity (Tierney et al., 2016). For these reasons, social difficulties can go unnoticed.

Some girls with autism will have a ‘special interest’. Although the intensity is similar to that of boys with autism, the special interest might not stand out as being unusual (e.g., animals, Disney, creative writing, Harry Potter, manga) and might be ‘gender typical’ (see Lawson, 2019, for a review). Girls might show preferences for routine and struggle with transitions; their rigidity can also present as strong opinions and can mean that they can be very determined. This tendency can make autistic girls wonderful advocates; Swedish teenage environmental activist Greta Thunberg is a testament to this. Like boys, some girls with autism show differences in their sensory processing; for example, they can be sensitive to light, sounds, the feeling of some fabrics, and self- grooming (e.g., having their hair brushed).

Why are girls missed? Girls are less likely to be referred for assessment (Rutherford et al., 2016), and referred girls are less likely to get a diagnosis of autism (Duvekot et al., 2017). Girls might cope with strong emotions by turning them inward (internalising, anxiety, depression) rather than outward (externalising, challenging behaviour), meaning they can fly under the radar. The diagnostic tools we use for autism have a male bias and are less effective for identifying females (Ratto et al., 2018). Diagnosticians who are unfamiliar with the female autism phenotype might carry this male bias, looking for the signs of autism they’re used to seeing in males; girls don’t necessarily fit the stereotype. As part of an assessment process, a range of information is gathered from clinical observations, self-, parent-, and teacher-report. Girls can seem different in the clinic, at school, and at home, which complicates the assessment process. For girls and women, there can be a marked difference between how they seem on the outside, and what they’re experiencing internally.

What should health professionals look for? A recent paper sums up the opinions of clinical psychologists experienced in assessing autism in girls with the title “exactly the same but completely different” (Muggleton, McMahon, & Johnston, 2019).  By interviewing the psychologists, the researchers found that while the psychologists believed the underlying characteristics of autism seemed the same across girls and boys, psychologists had noticed the way these characteristics presented seemed different. As a clinical psychologist, I (RJ) have personally found that when assessing girls and women, it can be important to look beyond surface social skills and toward deeper social understanding. Look for discrepancies between home and school; are they socially successful but then struggling at home from the effort? Consider a combination of age, cognitive/language ability, and anxiety, as these can help to decide whether social success is coming to them naturally or is effortful compensation. For young girls, investigate their imaginative play skills by changing the idea or script and seeing if they can follow and adapt flexibly. Drop social hints about yourself and see if they pick up on the cue to ask you a question. For women, listen to their descriptions of how they learned social skills and the difficulties they encountered along the way. Look carefully at co-occurring sleep, digestive issues, mood, and anxiety. When assessing for autism, it’s not just about looking, it’s about listening. People’s stories and experiences (including their own and those of parents and partners) can be as important as the behaviours observed in the clinic.

What does diagnosis mean for girls? An accurate autism diagnosis is important for girls and women. Receiving a diagnosis can give girls and women understanding, support, community, and a sense of identity, and can be liberating (Frith, 2013). Many women have received an incorrect diagnosis (Bargiela et al., 2016) on their way to identifying their autism, which can be confusing and lead to inappropriate or even harmful treatments. Increased self-awareness and understanding from others can help prevent some of the secondary difficulties (e.g., mental health concerns) associated with a lack of understanding and support.

What about males and non-binary people? Gender is more complicated than a simple male-female binary, and people with autism show more varied gender presentations (Strang et al., 2014). More research is needed to understand the presentation of autism across the gender spectrum and how autism presents in those who are gender diverse. Of course, there are also individual differences in how autism presents; the points made above can also apply to boys with autism and may not be exclusive to girls (Hull et al., 2019). This is because “the way autism affects individuals is highly variable” (Gould, 2017, p. 704).

By Dr Bec Flower and Dr Rachel Jellett, OTARC Postdoctoral Research Fellows