Sex differences in autism

Autism Spectrum Disorders (ASD) are currently more commonly diagnosed in males, with a ratio of about 1 female for every 4 males diagnosed. Currently, one in every 189 females and one in 42 males is diagnosed with Autism Spectrum Disorder (ASD). There is some evidence that females may also receive diagnoses somewhat later than males, however thus far results have been contradictory. Researchers have also debated whether a diagnostic gender bias has played a role in females being under diagnosed with Autism Spectrum Disorder. Researchers have speculated a gender bias in the parental reporting due to the expectations and socialization of gender roles in society. As of yet, there have been no studies specifically addressing the occurrence of autism in intersex individuals, and this is an area that requires further research. Several theories exist to explain the male-female sex based discrepancy, such as a genetic protective effect, the Extreme Male Brain Theory, and phenotypic differences in the presentation between sexes.

Differences in presentation of autistic traits are widely supported within the autistic community, and gaining support in the professional field. Hans Asperger was one of the first people to study autism, yet all of his four students were male. Another early researcher, Leo Kanner described "autistic disturbances of affective contact" in the group consisting of eight boys and three girls. Since biological differences exist between males and females, it follows that the presentation of autism would differ as well. Recent studies suggest this to be true, with evidence of increased incidence of social anxiety, anorexia nervosa, and self-harm in autistic females.

According to a female protective effect hypothesis more extreme genetic mutations are required for a girl to develop autism than for a boy. In 2012, Harvard researchers published findings suggesting that, on average, more genetic and environmental risk factors are required for girls to develop autism, compared to boys. The researchers analyzed DNA samples of nearly 800 families affected by autism and nearly 16,000 individuals with a variety of neurodevelopmental disorders. They looked for various types of gene mutations. Overall, they found that females diagnosed with autism or another neurodevelopmental disorder had a greater number of harmful mutations throughout the genome than did males with the same disorders.

Sexuality is often discussed within the autistic community, with many observations that identities other than cis-hetero seem to be more common than is observed in the neurotypical population. There have not been many formal studies on this to date, however members of the community speculate that autistic individuals generally have different ideals, perceptions, and desires than neurotypicals, or simply do not comprehend or agree with society's expectation, making them more apt to diverge from the norm.

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