The intersection of autism & gender dysphoria

In recent years, evidence emerged of a significant overlap between autism and gender dysphoria. As a trans person myself, I’ve followed this with interest, but most studies I found only measured autistic traits in patients at gender clinics, rather than reporting on diagnosed cases of autism. But that was years ago.

The number of publications on the suggested overlap between autism and gender dysphoria has more than doubled in the last 2–3 years.^[1]Autism Spectrum Disorder and Gender Dysphoria/Incongruence. A systematic Literature Review and Meta-Analysis (Kallitsounaki & Williams, 2020) So today, I think there has been enough research to draw firmer conclusions on the true intersection of autism and gender dysphoria. In this article, I will explore some of that research.

Gender incongruence & gender dysphoria

Before I look into the research, let me define two terms that will be relevant:

• Gender incongruence (GI) — A condition in which a person’s experienced gender does not align with their sex.^[2]Gender incongruence (Butler, 2020)
• Gender dysphoria (GD) — A condition in which a person’s experienced gender does not align with their sex, accompanied by clinically significant distress about this incongruence.^[3]Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR) (American Psychiatric Association, 2013)

Note that transgender people can experience either gender incongruence or gender dysphoria, but only the latter is a diagnosable condition as per the DSM-5. A trans person with gender dysphoria will experience great distress about their body, general appearance, and the way they’re perceived and treated not aligning with their sense of self, their proclivities, and their preferences. In my case, I became aware of this incongruence when I was around 8 years old, and this awareness and the distress experienced from this incongruence intensified during puberty. I ultimately acknowledged I was trans when I was 19.

Structure of this article

I’m going to explain the findings of a comprehensive study from 2020 by Aimilia Kallitsounaki & David M. Williams, which looked into a myriad of studies on autism and gender dysphoria/incongruence. This study consists of two parts:^[4]Autism Spectrum Disorder and Gender Dysphoria/Incongruence. A systematic Literature Review and Meta-Analysis (Kallitsounaki & Williams, 2020)

• Part 1: A systematic literature review on autism and gender dysphoria/incongruence
• Part 2: A meta-analysis of studies of autism diagnoses and autistic traits in people with gender dysphoria or gender incongruence

The first part will give an overview of the findings of various studies over the years, while the second part synthesizes the findings of all those studies to get some conclusive numbers on the actual overlap between autism and gender dysphoria. So if you want to get to the conclusion of the 2020 study, feel free to scroll down to part 2.

Part 1: Systematic review

The 2020 study identified 108 relevant studies, of which they excluded 61 because they did not fulfill their criteria (the criteria being that they should include reported quantitative results, be published in peer-reviewed journals, and written in English).^[5]Autism Spectrum Disorder and Gender Dysphoria/Incongruence. A systematic Literature Review and Meta-Analysis (Kallitsounaki & Williams, 2020)

Their systematic literature review ultimately included 47 studies that contained information on the overlap between autism and gender dysphoria. Of these studies:

• 5 were conducted with children
• 13 with children and adolescents
• 2 with adolescents
• 2 with children, adolescents, and adults
• 9 with adolescents and adults
• 16 with adults

Part 1a: Studies in the autistic population

Here are some relevant findings on gender dysphoria in the autistic population:^[6]Autism Spectrum Disorder and Gender Dysphoria/Incongruence. A systematic Literature Review and Meta-Analysis (Kallitsounaki & Williams, 2020)

• Several studies show that autistic people report a more diverse range of gender identities than neurotypicals on average.^[7]Sexuality and Gender Role in Autism Spectrum Disorder: A Case Control Study (Bejerot & Eriksson, 2014)^[8]Gender identity and sexual orientation in autism spectrum disorder (George & Stokes, 2018)
• A 2018 study found that parents of autistic children reported significantly more gender variance in their children than parents of neurotypical children.^[9]Gender Variance and the Autism Spectrum: An Examination of Children Ages 6–12 Years (Natisha Nabbijohn et al., 2018)
• A 2019 study found that diagnosed autistic children were over 4 times more likely to have a co-occurring diagnosis of gender dysphoria than neurotypical children.^[10]Gender Dysphoria in Children with Autism Spectrum Disorder (Hisle-Gorman et al., 2019)
• A 2017 study found that 15.4% of autistic participants reported trans, nonbinary, and other gender identities.^[11]Sexual Orientation, Gender Identity, and Romantic Relationships in Adolescents and Adults with Autism Spectrum Disorder (DeWinter, De Graaf, & Begeer, 2017)
• A 2018 study found that 15% of autistic participants reported trans and nonbinary identities.^[12]Brief Report: Gender Identity Differences in Autistic Adults: Associations with Perceptual and Socio-cognitive Profiles (Walsh et al., 2018)
• A 2018 study found that autistic people were significantly more likely to have gender dysphoria, and to plan to have a gender transition than neurotypicals.^[13]Gender Identity in Autism: Sex Differences in Social Affiliation with Gender Groups (Cooper, Smith & Russell, 2018)
• A 2020 study found that autistic females were less likely to identify with their birth-assigned sex than neurotypical females.^[14]Gender identity, sexual orientation and adverse sexual experiences in autistic females (Pecora et al., 2020)

Keep in mind that the prevalence of autism in the general population is up to 2.76%.^[15]Data & Statistics on Autism Spectrum Disorder | CDC

Part 1b: Studies in the gender dysphoria population

Prevalence of autism diagnoses

Some of the relevant findings on the prevalence of diagnosed autism in people with gender dysphoria or gender incongruence include:^[16]Autism Spectrum Disorder and Gender Dysphoria/Incongruence. A systematic Literature Review and Meta-Analysis (Kallitsounaki & Williams, 2020)

• A 2010 study found that of their sample of 204 gender-referred individuals, 7.8% were autistic.^[17]Autism Spectrum Disorders in Gender Dysphoric Children and Adolescents (de Vries et al., 2010)
  • Among adolescents diagnosed with gender dysphoria, 6.5% received a co-occurring diagnosis of autism.
  • Among children diagnosed with gender dysphoria, 1.9% were diagnosed with autism.
• In prerecorded clinical chart data of children and adolescents with gender dysphoria or gender incongruence, the prevalence of autism diagnoses ranged from 3 to 21.3%.^[18]Mental Health of Transgender and Gender Nonconforming Youth Compared With Their Peers (Becerra-Culqui et al., 2018)^[19]Characteristics of Referrals for Gender Dysphoria Over a 13-Year Period (Chen, Fuqua & Eugster, 2016)^[20]Characteristics of Adolescents Referred to a Gender Clinic: Are Youth Seen Now Different from Those in Initial Reports? (Chiniara, Bonifacio & Palmert, 2018)^[21]Young people with features of gender dysphoria: Demographics and associated difficulties (Holt, Skagerberg, & Dunsford, 2016)^[22]Clinical Management of Youth with Gender Dysphoria in Vancouver (Khatchadourian, Amed, & Metzger, 2014)^[23]Traits of autism spectrum disorder in school-aged children with gender dysphoria: A comparison to clinical controls (Leef et al., 2019)^[24]Mental Health Concerns and Insurance Denials Among Transgender Adolescents (Nahata et al., 2017)^[25]Suicidality, Self-Harm, and Body Dissatisfaction in Transgender Adolescents and Emerging Adults with Gender Dysphoria (Peterson et al., 2017)^[26]Evaluation of Asperger Syndrome in Youth Presenting to a Gender Dysphoria Clinic (Shumer et al., 2016)^[27]Brief Report: Autistic Features in Children and Adolescents with Gender Dysphoria (Skagerberg, Di Ceglie, & Carmichael, 2015)^[28]Children and Adolescents With Gender Identity Disorder Referred to a Pediatric Medical Center (Spack et al., 2012)
• In clinical chart data of adults with gender dysphoria or gender incongruence, the prevalence of autism diagnoses ranged from 4.8 to 7.8%.^[29]Sociodemographic and Clinical Characteristics of Transgender Adults in Australia (Cheung et al., 2018)^[30]Individuals seeking gender reassignment: marked increase in demand for services (Fielding & Bass, 2018)^[31]The Co-occurrence of Gender Dysphoria and Autism Spectrum Disorder in Adults: An Analysis of Cross-Sectional and Clinical Chart Data (Heylens et al., 2018)

Prevalence of autism caseness

Caseness means cases where scores are high to be classed as a clinical case, but which lack diagnoses. In other words, cases where an autism diagnosis would likely be applicable but no formal diagnosis has been conducted. Some of the relevant findings on the prevalence of autism caseness in people with gender dysphoria or gender incongruence include:^[32]Autism Spectrum Disorder and Gender Dysphoria/Incongruence. A systematic Literature Review and Meta-Analysis (Kallitsounaki & Williams, 2020)

• Studies indicate that the autism rate among children and adolescents with gender dysphoria or incongruence ranges from 14.5 to 68%.^[33]Autistic Traits and Executive Functions in Children and Adolescents With Gender Dysphoria (Akgül et al., 2018)^[34]Traits of autism spectrum disorder in school-aged children with gender dysphoria: A comparison to clinical controls (Leef et al., 2019)^[35]Mental Health Correlates of Autism Spectrum Disorder in Gender Diverse Young People: Evidence from a Specialised Child and Adolescent Gender Clinic in Australia (Mahfouda et al., 2019)^[36]Evaluation of Asperger Syndrome in Youth Presenting to a Gender Dysphoria Clinic (Shumer et al., 2016)^[37]Brief Report: Autistic Features in Children and Adolescents with Gender Dysphoria (Skagerberg, Di Ceglie, & Carmichael, 2015)^[38]Autism Spectrum Disorder Risk Factors and Autistic Traits in Gender Dysphoric Children (VanderLaan & Leef et al., 2015)^[39]Autistic Symptoms in Children and Adolescents with Gender Dysphoria (van der Miesen & de Vries et al., 201)
• Studies indicate that the autism rate among adults with gender dysphoria or incongruence ranges from 1.2 to 40.3%.^[40]The Co-occurrence of Gender Dysphoria and Autism Spectrum Disorder in Adults: An Analysis of Cross-Sectional and Clinical Chart Data (Heylens et al., 2018)^[41]Brief Report: Female-To-Male Transsexual People and Autistic Traits (Jones et al., 2012)^[42]Autistic Traits in an Internet Sample of Gender Variant UK Adults (Kristensen & Broome, 2015)^[43]Autism trait prevalence in treatment seeking adolescents and adults attending specialist gender services (Lehmann et al., 2020)^[44]Autism and transgender identity: Implications for depression and anxiety (Murphy et al., 2020)^[45]Autistic Traits in Treatment-Seeking Transgender Adults (Nobili et al., 2018)^[46]The stability of autistic traits in transgender adults following cross-sex hormone treatment (Nobili et al., 2020)^[47]Traits of Autism Spectrum Disorders in Adults with Gender Dysphoria (Pasterski, Gilligan, & Curtis, 2014)^[48]Autistic traits in individuals self-defining as transgender or nonbinary (Stagg & Vincent, 2019)^[49]Self-Reported Autism Spectrum Disorder Symptoms Among Adults Referred to a Gender Identity Clinic (Vermaat et al., 2018)
• However, the autism caseness ranges widely depending on the cutoff scores used. For example, a 2014 study found that 5.5% of transgender adults diagnosed with gender dysphoria or gender incongruence scored ≥ 32 on the Autism Spectrum Quotient (AQ), suggesting clinically significant levels of autistic traits;^[50]Traits of Autism Spectrum Disorders in Adults with Gender Dysphoria (Pasterski, Gilligan, & Curtis, 2014) but a 2014 study found that 39% of gender-variant adults should be referred for a diagnostic assessment of autism based on scores of > 6 on the AQ-10.^[51]Autistic Traits in an Internet Sample of Gender Variant UK Adults (Kristensen & Broome, 2015) Personally, I question whether the AQ-10 is sufficient for referral since it has only 10 questions, and a threshold of 6 seems fairly low. The autism rate would probably drop to a percentage closer to the 2014 findings if the threshold were raised to 8. However a threshold of 8 would also miss many autistics due a higher probability of outliers.

Prevalence of autistic traits

To examine the prevalence of autistic traits in people with gender dysphoria or gender incongruence, researchers have used parent and self-report measures that index autism characteristics. Some of the relevant findings of these studies include:^[52]Autism Spectrum Disorder and Gender Dysphoria/Incongruence. A systematic Literature Review and Meta-Analysis (Kallitsounaki & Williams, 2020)

• Two studies from 2014 and 2017 found elevated obsession in children referred to gender clinics, compared to non-referred and clinic-referred children (clinic-referred means children referred based on the Teacher’s Report Form, which assesses problem behavior). A significant increase in compulsion was also reported in gender-referred children compared to non-referred children.^[53]Do Children With Gender Dysphoria Have Intense/Obsessional Interests? (VanderLaan et al., 2014)^[54]Intense/obsessional interests in children with gender dysphoria: a cross-validation study using the Teacher’s Report Form (Zucker et al., 2017)
• A 2017 study used the Children’s Social Behavior Questionnaire (CSBQ), and found significantly increased autistic traits in children with gender dysphoria, compared to neurotypical children used as a control group.^[55]Autistic Symptoms in Children and Adolescents with Gender Dysphoria (van der Miesen & de Vries et al., 2017)
• A 2018 study used the Social Responsiveness Scale (SRS) and found that children who satisfied the diagnostic criteria for gender dysphoria had significantly more autistic traits than the non-autistic control group.^[56]Autistic Traits and Executive Functions in Children and Adolescents With Gender Dysphoria (Akgül et al., 2018)
• A 2019 study used the Social Communication Questionnaire and found elevated autistic traits in children with gender dysphoria.^[57]Traits of autism spectrum disorder in school-aged children with gender dysphoria: A comparison to clinical controls (Leef et al., 2019)
• A 2018 study used the Social Responsiveness Scale and found increased autistic traits in adults diagnosed with gender dysphoria, compared to a normative sample.^[58]The Co-occurrence of Gender Dysphoria and Autism Spectrum Disorder in Adults: An Analysis of Cross-Sectional and Clinical Chart Data (Heylens et al., 2018)
• Studies from 2012 and 2018, and 2020 used the AQ and found that transgender men reported significantly more autistic traits than non-clinical males and females. No difference was found between transgender women and non-clinical males and females.^[59]Brief Report: Female-To-Male Transsexual People and Autistic Traits (Jones et al., 2012)^[60]Autistic Traits in Treatment-Seeking Transgender Adults (Nobili et al., 2018)^[61]The stability of autistic traits in transgender adults following cross-sex hormone treatment (Nobili et al., 2020)
• A 2020 study found that transgender men and non-binary females reported significantly more autistic traits than control females from the general population. But just as the previous studies found, no difference was observed between either transgender women or non-binary males and control males from the general population.^[62]Autism and transgender identity: Implications for depression and anxiety (Murphy et al., 2020)
• A 2018 study found that women referred for gender dysphoria reported significantly more autistic traits as per the AQ than control women—as well as compared to one of the three control samples of men. Men who were referred for gender dysphoria scored significantly lower on the AQ than control males. No difference was found between men referred for gender dysphoria and control females.^[63]Self-Reported Autism Spectrum Disorder Symptoms Among Adults Referred to a Gender Identity Clinic (Vermaat et al., 2018)
• A 2019 study based on self-reports found that transgender and non-binary adults reported significantly more autistic traits than cisgender adults.^[64]Autistic traits in individuals self-defining as transgender or nonbinary (Stagg & Vincent, 2019)
• A 2020 study (the largest study on this topic conducted to date) replicated these findings.^[65]Elevated rates of autism, other neurodevelopmental and psychiatric diagnoses, and autistic traits in transgender and gender-diverse individuals (Warrier et al., 2020)

Part 2: Meta-analysis

Of the 47 studies included in the literature review of the 2020 study by Kallitsounaki & Williams,^[66]Autism Spectrum Disorder and Gender Dysphoria/Incongruence. A systematic Literature Review and Meta-Analysis (Kallitsounaki & Williams, 2020) the aforementioned largest study from 2020 consisted of 5 independent datasets,^[67]Elevated rates of autism, other neurodevelopmental and psychiatric diagnoses, and autistic traits in transgender and gender-diverse individuals (Warrier et al., 2020) which were counted as separate studies, for a total of 51. Of those, 6 studies were excluded (read ‘Sample of Studies’ of the Method section if you’re curious why), for a total of 45 studies.

Part 2a: Diagnosed autism & gender dysphoria

Of the 45 studies, 25 studies were included in the meta-analysis of diagnosed autism in people with gender dysphoria or gender incongruence, with a total of 8,662 participants with GD/GI.^[68]Autism Spectrum Disorder and Gender Dysphoria/Incongruence. A systematic Literature Review and Meta-Analysis (Kallitsounaki & Williams, 2020) Of those 25 studies:

• 12 were conducted primarily with adults
• 3 were conducted primarily with adolescents
• 9 were conducted primarily with children and adolescents
• 1 one was conducted with children

Results

Results from the analysis showed that the pooled estimate of the prevalence of autism diagnoses in people with gender dysphoria or gender incongruence was 11%. This is quite significant, since the prevalence of autism in the general population is up to 2.76%.^[69]Data & Statistics on Autism Spectrum Disorder | CDC This suggests that people with gender dysphoria or gender incongruence are almost 4 times more likely than the general population to be autistic!

Variance

However, the effect sizes included in the analysis showed a lot of variance between studies, meaning that the association between diagnosed autism and gender dysphoria varied depending on the studies. Several analyses were performed to explore this variance. The results of these analyses show that:

• The prevalence estimate of autism diagnoses was higher among participants with suspected gender dysphoria than those with a diagnosis of gender dysphoria and people referred to specialized clinics for gender dysphoria. The study doesn’t reveal why that is
• The prevalence estimate from clinical-based studies was lower than that from population-based studies
• Neither the mean age of participants nor the percentage of birth-assigned males in the sample significantly predicted the prevalence estimate of autism diagnoses

Part 2b: Autistic traits & gender dysphoria

Of the 45 studies, 11 studies were included in the meta-analysis of autistic traits in people with gender dysphoria or gender incongruence, with a total of 4,664 participants with GD/GI.^[70]Autism Spectrum Disorder and Gender Dysphoria/Incongruence. A systematic Literature Review and Meta-Analysis (Kallitsounaki & Williams, 2020) Of those 11 studies:

• 8 were conducted primarily with adults
• 3 were conducted primarily with children and adolescents

Results

Results from the analysis revealed that:

• There was a moderate mean difference (g = 0.67) in reported autistic traits between people with gender dysphoria or gender incongruence and control participants.
• On average, people with gender dysphoria or gender incongruence reported more autistic traits than control participants.

Variance

The results indicated a high variance in the association between autistic traits and GD/GI between studies, so several analyses were performed to explore the sources of this variance. However, none of the variables contributed meaningfully to this variance:

• No significant difference was found between studies that used secondary and primary sources of data for their control groups; in both cases, GD/GI participants showed elevated autistic traits compared to control participants
• No significant difference was found between clinical-based studies and population-based studies
• No significant difference was found between studies conducted among children and studies conducted among adults

Conclusions

The findings of the literature review and meta-analyses indicate that:

• There is a positive relationship between autistic traits and gender dysphoria/incongruence among people from the general population
• There is an increased prevalence of gender dysphoria and gender incongruence in the autistic population
• There is an increased prevalence of autism diagnoses and autistic traits in the GD/GI population

Taken together, the paper shows a definite link between autism and gender dysphoria or gender incongruence. I’m looking forward to more research investigating mechanisms that could explain this link. I’ve seen some suggestions that could account for or contribute to this association, but I will cover that in a future article.