Gender differences in autism

Liliya John is a researcher at Altogether Autism

30 May 2017 – Flying under the radar, slipping through the net or hiding in plain sight?

There is limited information regarding autism in the female population and what we know about autism is mostly about autism in males. Liliya John writes that since the beginning, our understandings of autism have always been from a male perspective and this knowledge gap in terms of gender may have contributed to many females ‘flying under the radar’. Research clearly indicates the possibility of a diagnostic gender bias, meaning females who meet the criteria for autism are at disproportionate risk of not receiving a clinical diagnosis.

ONE OF THE most consistent characteristics of autism is the inconsistency with which it affects men and women.

Autism is approximately four times more common among males than females and the frequently stated sex ratio is 4:1 (Hallady et al., 2015). However, according to a latest study by researchers at the University College, London, the true male-to-female ratio of children meeting the criteria for autism is not 4:1, as is often assumed; rather, it is closer to 3:1 (Loomes et al., 2017). In addition to prevalence rates, research also indicates that males and females may have different autism profiles, i.e., they may differ in the ways in which they exhibit both the strengths and difficulties of autism (Lai et al., 2015).

Why does this gender difference in diagnosis occur? Why do many girls and women go undiagnosed? Are women less vulnerable to autism? Does autism look different in girls, making it harder to detect or diagnose? What are the differences between girls and boys with autism? Even though autism and gender difference is widely researched, we do not have clear cut answers for these questions yet.

One of the strong arguments for why autism might be missed in females has been linked to diagnostic criteria itself.  Historically speaking, ever since the first published descriptions of autism by Leo Kanner and Hans Asperger in the 1940s, it was primarily conceptualised as affecting only males. All four of the participants from Hans Asperger’s study were boys and eight of the 11 cases described by Kanner were boys (Werling et al., 2013). Asperger even believed that autism was specific to boys even though clinical evidence made him change his assumption later.  Asperger (1944/1991) commented: “It may be only chance that there are no autistic girls among our cases or it could be that the autistic traits in females only become evident after puberty. We just do not know” (p. 85).

Also, there is far more research on males with autism than females with autism. Studies either tend to recruit four male participants for every one female participant or they completely exclude female participants (Lai et al., 2015). Since the diagnostic criteria for autism is developed based on research and considering that females are underrepresented in most clinical samples, the diagnostic criteria itself is biased. This in turn reinforces the male bias in diagnostic tools and instruments, perpetuating the exclusion of females in the way autism is both defined and diagnosed (Haney, 2016).

Research findings on gender differences in autism

  • Females show less restricted and repetitive behaviours and interests compared to boys (Frazier et al., 2014; Zwaigenbaum et al., 2012; Van Wjingaarden-Cremers et al., 2014).  The presence of repetitive behaviour and special interests is a key diagnostic criterion and clinicians often look for examples around stereotypically “male” interests, such as train timetables and numbers during the diagnostic process (Supekar et al., 2015). However, girls with autism do not necessarily have the same kinds of special interests as typical autistic boys, and their interests are similar to those in typically developing girls, such as fascination with dolls, horses, pop stars and celebrities, Disney films etc. which are socially accepted. These differences in special interests and behaviours could be one reason why many females slip through the net when it comes to diagnosis.
  • Females require more severe autistic symptoms and more complex behavioural and cognitive symptoms to be diagnosed with autism (Frazier et al., 2014; Bargiela et al., 2016). One study found that if boys and girls had a similar level of autistic traits, the girls needed to have either more behavioural problems or significant intellectual disability, or both, to be diagnosed (Dworzynski et al., 2012). Hence, females with a higher IQ or less severe symptoms stand at a risk of missing a diagnosis (Van Wjingaarden-Cremers et al., 2014).
  • Girls tend to have internalising symptoms such as depression, anxiety and eating disorders whereas boys tend to have more externalising symptoms such as aggression, and hyperactivity (Altman et al., 2016). When girls with internalising symptoms are referred to professionals, the symptoms often get misinterpreted and misdiagnosed as those of anxiety, avoidant personality disorder and eating disorders.
  • Many autistic women miss diagnoses due to their ability to camouflage or mask their social difficulties by mimicking socially appropriate behaviour. They also may have higher social motivation and a greater capacity for traditional friendships than males with autism (Bargiela et al., 2016).

What are the benefits of improved understanding of autism in girls?

Research on gender differences could help in the development of non-biased diagnostic criteria and diagnostic instruments in future.

  • It will raise awareness among health professionals who are involved in early identification and diagnosis of autism. It would help diagnose women those who would otherwise be undiagnosed.
  • Understanding of how autism presents differently in females will also help in understanding their different needs and providing them with the right supports and interventions.
  • It could also help to understand whether transitions differ in both sexes and if yes, how do we help girls to have  successful transitions?

Read the latest Altogether Autism journal.

References

Altman, L., & Turk, J. (2016). Comparison of autistic profiles in young females and males with autism spectrum disorder: A review of the literature. Journal of the American Academy of Child and Adolescent Psychiatry, 1(55).

Asperger, H. (1991). Autistic Psychopathy in Childhood (U. Frith, Trans.). In U. Frith (Ed.),

Asperger and his syndrome (pp. 37–92). Cambridge, UK: Cambridge University Press. (Original work published 1944).

Bargiela, S., Steward, R., & Mandy, W. (2016). The experiences of late-diagnosed women with Autism Spectrum Conditions: An investigation of the female autism phenotype. Journal of Autism and Developmental Disorders, 46(10), 3281-3294.

Dworzynski, K., Ronald, A., Bolton, P., & Happe, F. (2012). How different are girls and boys above and below the diagnostic threshold for autism spectrum disorders? Journal of the American Academy of Child and Adolescent Psychiatry, 51(8), 788-797.

Frazier, T.W., Georgiades, S., Bishop, S.L., & Hardan, A.Y.  (2014). Behavioral and cognitive  characteristics of females and males with autism. Journal of American Academy of Child and Adolescent Psychiatry, 53(3), 329-40.

Halladay, A. K., Singer, A. T., Bishop, S. N., Constantino, J. M., Daniels, A. J., Koenig, K. L., . . . Szatmari, P. (2015). Sex and gender differences in autism spectrum disorder: Summarizing evidence gaps and identifying emerging areas of priority. Molecular Autism, 6(1), 36.

Haney, J.L. (2016) Autism, females, and the DSM-5: Gender bias in autism diagnosis. Social Work in Mental Health, 14(4), 396-407.

Lai, M.C., Lombardo, M. V., Auyeung, B., Chakrabarti, B., & Baron-Cohen, S. (2015). Sex/gender differences and autism: Setting the scene for future research. Journal of the American Academy of Child and Adolescent Psychiatry, 54(1), 11–24.

Loomes, R., Hull, L., & Mandy, W.P.L. (2017). What is the male-to-female ratio in autism spectrum disorder? a systematic review and meta-analysis. Journal of the American Academy of Child and Adolescent Psychiatry. doi.org/10.1016/j.jaac.2017.03.013

Supekar, K., & Menon, V. (2015). Sex differences in structural organization of motor systems  and their dissociable links with repetitive/restricted behaviours in children with autism.  Molecular Autism, 6(1), 50.

Van Wijngaarden-Cremers, P. J., van Eeten, E., Groen, W. B., van Deurzen, P. A., Oosterling, I. J., & van der Gaag, R. J. (2014). Gender and age differences in the core triad of impairments in autism spectrum disorders: A systematic review and meta-analysis. Journal of Autism and Developmental Disorders, 44(3), 627–635.

Werling, D. M., & Geschwind, D. H. (2013). Sex differences in autism spectrum disorders. Current Opinion in Neurology, 26(2), 146–153.

Zwaigenbaum, L., Bryson, S. E., Szatmari, P., Brian, J., Smith, I.M., & Roberts, W. (2012). Sex differences in children with autism spectrum disorder identified within a high-risk infant cohort. Journal of Autism and  Developmental Disorders, 42, 2585–96.