The prevalence of Autism Spectrum Disorder is significantly higher in males than in females. While the difference has narrowed in recent years, evidence still supports that poor recognition and understanding of the autistic* female phenotype has significantly affected the difference in prevalence. Overall there are more similarities than differences between autistic girls and boys, but the differences that exist, and bias among professionals and their diagnostic tools, may account for some of the large discrepancy. Some of the ways autism presents differently in females than males are:
the amount or types of restricted, repetitive patterns of behavior and interests
language and gesture use
the ability to imitate social skills
the cognitive skills of executive function and theory of mind
and sensory challenges.
Researchers and health professionals need a better understanding of the differences to be able to recognize and effectively care for autistic women and their unique presentation.
Overall prevalence of ASD in the United States has increased in recent years and is now believed to be about 1 in 68 children, with an overall prevalence of 1%. The prevalence of autism in females varies, with studies citing a ratio of 4-5:1 of males to females as an average. This ratio is increased in those who require fewer supports, sometimes called “high functioning” to 8-10:1, but drops to approximately 2:1 in individuals with intellectual disability (ID). In other words, women and girls are better identified when ID exists, but less represented with typical or higher intellect.
Though newer studies show narrowing ratios of 2-2.6:1 or 3.5:1, the discrepancy remains much higher at a younger age, decreasing over time in adolescence and adulthood. This reflects the overall tendency for females to be diagnosed as a much later age than males.
Restricted, Repetitive Patterns of Behavior, Interests, or Activities
Restricted, repetitive patterns of behavior, interests, or activities (RRBI) is an important diagnostic criterion for autism in the DSM 5, yet there are differences in RRBI among females as compared to males. Females may have fewer restricted interests and repetitive behaviors than boys, or they may be ‘atypical’. These atypical RRBI may involve social interests, such as playing with dolls or mimicking others, and due to their social nature may play a role in masking female autism. Others, such as restricted and rigid diets may contribute to alternate diagnoses like anorexia nervosa. This is a condition often equated with girls, thus causing the underlying autism to be missed. Interestingly, approximately 23% of those with anorexia nervosa are autistic, a rate that far exceeds the general population.
Language and Gestures
Autistic individuals use fewer words in storytelling, especially as they relate to the internal and mental states of others. Females on the autism spectrum are noted to use more words describing internal states and explained internal states more often than boys with ASD. Girls may use more “vivid” gestures while communicating, showing increased energy and more visibility to examiners. The use of more vivid gestures may help mask communication deficits. In other communication areas results were mixed, with girls showing some advantage over boys in some studies and others showing no difference.
Observation and Imitation
Numerous reports note that autistic females have a greater ability than males to observe and imitate others by copying mannerisms, voice, and persona. This is a form of social echolalia, where she acts the part of another person. For some females, the need to observe and systemize human social interaction, and therefore behave in a more socially appropriate way, is her restricted interest or RRBI. Experts often describe this as “camouflaging” autism. Females are often believed to be more self-aware and in some cases, make extra effort to camouflage themselves to fit in.
Findings are mixed as to whether there is any difference for females in developing and maintaining friendships than males, but when they exist the problems are different. This may mean that females have greater ability to initiate friendship but greater impairment than males in maintaining them.
While in the general population, women have higher levels of empathy than men; in ASD, both women and men have a diminished ability to display outward signs of empathy towards others. Women in one study self-reported levels of empathy more like typically-developed men than typically-developed women. Expectations are often greater of autistic women than autistic males to display sensitivity and empathy, as these are qualities attributed to women, and autistic females may have greater abilities in this area than autistic males.
Executive Function and Theory of Mind
There is some evidence of increased challenges with executive function in females as compared to males. Per a large systematic review, there are no differences noted in theory of mind skills. Despite this, milder impairments were seen in results of the Autism Diagnostic Observation Schedule (ADOS), a diagnostic test used by educators and clinicians. This is one reason why the validity of the ADOS in girls in under question.
Though not part of the diagnostic criteria for ASD, sensory issues or “unusual sensory responses” are common in autistic individuals and account for a large portion of the heterogeneity in autistic expression. Sensory issues can have a significant impact on daily life and function. While women and girls may have more sensory challenges then men and boys, there is little information to help understand what constitutes those differences.
Autism has long been considered a male condition; thus bias, along with the different expression in women, limit the ability to identify women and girls on the spectrum. Common screening and diagnostic tools such as the ADOS, Autism Spectrum Quotient, and Social Communication Questionnaire were developed based on the autistic male phenotype and capture behaviors biased towards males. For example, women are less likely to meet criteria per the ADOS, even when they meet clinical criteria for autism.
Only one screening tool specifically includes the female phenotype: ASSQ-GIRL. This questionnaire, which relies on parent report rather than self-report or observation, is minimally researched and has yet to show much benefit in screening females.
Though there are more similarities than differences between male and female autistic phenotypes, the differences tend to mask autism in women. The diagnostic tests for autism have questionable validity for use in females and often fail to identify those without intellectual disability. Combine this with male bias, even if implicit, and the result is many females who are not screened, not referred, or misdiagnosed. In order to further our understand, females need to be better represented in research, with comparisons to both autistic males and neurotypical females. More inclusive screening and diagnostic tools need to be developed and researched. Clinicians need greater awareness that autism effects females, and that there is a different autistic female phenotype, and need further support in identifying and screening autistic girls at a younger age. Additionally, given the unknowns about autistic women and the lack of specific diagnostic tools, even psychiatric care providers should consider referrals to ASD specialists for the most accurate assessment of women.
Due to significant comorbidities associated with ASD, when women present with depression, anxiety, anorexia nervosa, or other psychiatric disorders, underlying ASD should be considered. Lastly, given the difficulties in identifying women with ASD, all providers should learn about autism and its different presentations in men and women, expecting that they will care for many individuals, and particularly women, who are undiagnosed.
About the author
Carrie Dickson is a Nurse-Midwife, nursing instructor, DNP student, community leader of the Health Professions Autism Network, co-founder of the Facebook community Autistic and Pregnant, Parenting, or Planning, and mother of 3 boys (one on the autism spectrum). For more information you can read her full, unpublished manuscript on this topic.