Not Just a Boys’ Club: Gender Disparity in Autism

For a condition that affects the lives of so many, startlingly little is known about autism. Even something so seemingly fundamental as exact causes remains a mystery. Despite these limitations, what is known is that Autism Spectrum Disorder (ASD) disproportionally affects males, with males diagnosed outnumbering females approximately 4:1 (Werling, 2013). This has led to a widespread belief—conscious or unconscious—that autism is a disorder that almost exclusively affects men. While true that there is medical evidence supporting the increased prevalence of ASD in males, it is also believed that ASD in females is very underdiagnosed, due in part to male-biased diagnostic models and differences in symptom expression across genders. With more and more researchers emphasizing sex- and gender-inclusive autism studies, it is important to understand the necessity of this new emphasis and how it builds on antiquated gender norms in ASD.

Figure 1. Symptoms considered “universal” for ASD are shown, although expression of some of these symptoms (eg. social deficit) is less prevalent/apparent across genders

One large, systemic issue affecting gender disparity in autism is the male-normative diagnostic model—the criteria that doctors are look for when making diagnoses are “‘based on the average patient being a male, 75-kilogram white patient’” (Bairey, 2019). While this issue of biological sex affecting diagnosis is widespread throughout the medical field, ASD is an especially complex case as “males may show more of the behaviors that trigger a clinical evaluation, such as hyperactivity and aggression,” whereas females’ seemingly more apparent socialness may lead to their symptoms being “misinterpreted and accurate diagnosis [being] delayed” (Halladay, 2015). 

At the same time, diagnostic differences do not comprise the full range of gender discrepancies in ASD; there is evidence supporting a female protective effect, wherein females are shown to exhibit genetic protection from certain diseases, meaning that “females with ASD are likely to be carrying a higher heritable mutational ‘load’ than affected males” (Werling, 2013). Simply put, this means that for females to have autism, they have to carry more mutated, atypical DNA than do males. This may be connected to findings that suggest greater exposure to testosterone as a fetus, which will naturally occur with males, will lead to varied expression of autistic traits (Zhang, 2020). 

Figure 2. Females with ASD have more genetic mutations and loss of function (LoF) than males (* = p < 0.01, N.S. = not significant)

Finally, the ASD gender gap can be partially attributed to a difference in “masking” behaviors. “Masking” can be defined as acting in a way that hides or makes less obvious the symptoms of autism (Deolinda, 2021). It is a learned skill that can help prevent social exclusion by helping people to “blend in,” which can simultaneously be an exhausting effort to be putting on an “act”. Masking is especially evident in social situations, with girls with autism being “more socially motivated,” leading to them having “friendships that were more intimate than those of boys with autism” (Sedgewick, 2016). Thus, girls are “punished” for being seemingly more socially adept: their lack of social deficit may prevent or delay diagnosis, especially in those who are more high-functioning (Werling, 2013).

Despite these factors leading to differential treatment, the inequitable medical and social climate is not entirely hopeless. There have been significant strides within current medical practice to address the issue of gender in medicine in general, but also in ASD, in particular. The new DSM-V diagnostic criteria for autism include demonstrated social deficit—which, again, may not be as apparent in girls—but also repetitive behaviors, which do not seem to be expressed significantly differently across sexes (Centers for Disease Control and Prevention, 2020). There is also a push for more representation of females in ASD studies, which was pointedly missing in the past. A recent study by the Stanford University School of Medicine analyzed brain scans of 637 boys and 136 girls with autism to develop an AI algorithm that could distinguish between the sexes purely from the scans; it was “challenging” to find female scans to include in the study as the “small number of girls historically included in autism research has been a barrier to learning more about them” (Digitale, 2022). Still, this study does make an effort to address these issues while also providing encouraging results. For example, one of the principal findings of this work showed that the AI algorithm demonstrated an 86% accuracy in distinguishing the boys’ scans from the girls’. At the same time, the algorithm, notably, struggled to distinguish between the sexes of children with typical neural development, showing that the differences in brain structure and activity found between the sexes were autism-specific (Digitale, 2022). 

Thus, however slow it seems, there is steady progress being made in the field of autism studies to pinpoint possible causes that may in turn lead to updated prevention and treatment. Thanks to a continual push for greater equity, the future of the medical world appears to be trending towards a less sex-segregated one.

Edited by Richard Lee

References

Bairey Merz, C. N., &amp; Kilpatrick, S. J. (2019). Examining gender bias in medical care. Cedars Sinai. Retrieved February 24, 2022, from https://www.cedars-sinai.edu/research/news/cedars-science/2019/examining-gender-bias-in-medical-care.html

Centers for Disease Control and Prevention. (2020, June 29). Autism spectrum disorder (ASD): Diagnostic criteria. Centers for Disease Control and Prevention. Retrieved February 24, 2022, from https://www.cdc.gov/ncbddd/autism/hcp-dsm.html

Deolinda, A. R. B. (2021, October 12). Blending into the crowd: What is autism masking? Autism Parenting Magazine. Retrieved March 7, 2022, from https://www.autismparentingmagazine.com/autism-masking/

Digitale, E. (2022, February 17). Study shows differences between brains of girls, boys with autism. ScienceDaily. Retrieved February 24, 2022, from https://www.sciencedaily.com/releases/2022/02/220217181733.htm

Halladay, A. K., Bishop, S., Constantino, J. N., Daniels, A. M., Koenig, K., Palmer, K., Messinger, D., Pelphrey, K., Sanders, S. J., Singer, A., Taylor, J., & Szatmari, P. (2015, June 13). Sex and gender differences in autism spectrum disorder: Summarizing evidence gaps and identifying emerging areas of priority. Molecular Autism. Retrieved February 23, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4465158/

Sedgewick, F., Hill, V., Yates, R., Pickering, L., &amp; Pellicano, E. (2016, April). Gender differences in the social motivation and friendship experiences of autistic and non-autistic adolescents. Journal of autism and developmental disorders. Retrieved February 24, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4786616/

Werling, D. M., & Geschwind, D. H. (2013, April). Sex differences in autism spectrum disorders. Current Opinion in Neurology. Retrieved February 23, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4164392/

Zhang, Y., Li, N., Li, C., Zhang, Z., Teng, H., Wang, Y., Zhao, T., Shi, L., Zhang, K., Xia, K., Li, J., & Sun, Z. (2020, January 15). Genetic evidence of gender difference in autism spectrum disorder supports the female-protective effect. Nature News. Retrieved February 23, 2022, from https://www.nature.com/articles/s41398-020-0699-8

Image References

Springer Nature Limited. (2020). Mutation load of functional classes of DNMs in the coding region. Retrieved February 23, 2022, from https://www.nature.com/articles/s41398-020-0699-8/figures/1.

Universal Symptoms of Autism. (2021). Verywell Health. Retrieved February 24, 2022, from https://www.verywellhealth.com/thmb/J0mjXfkmMvxVb5xpCpAo5RZJ2b4=/614×0/filters:no_upscale():max_bytes(150000):strip_icc():format(webp)/the-spectrum-of-autism-symptoms-5094373_final-a6bb13ecff7c4ff693002c84f808e5c2.jpg.

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