Are There Really More Autistic Boys Than Girls?

Girl Not Playing with Others
Girl Not Playing with Others. Getty/Fuse

Read any source on autism, and you'll learn that boys and men with the diagnosis outnumber girls and women by a factor of at least 4:1. The gender gap increases with higher functioning individuals (those who would, in the past, have been diagnosed with Asperger syndrome) to something like 11:1.

The idea that autism is a "male disorder" has become so well-established that some researchers (particularly Simon Baron-Cohen) have described autism as the manifestation of an "extreme male brain." Baron-Cohen points to traits such as apparent lack of empathy, focus on details and ordering, talents in the areas of math and science, and a preference for routine, saying that these are all manifestations of "maleness," and are also very common in autism.

Baron-Cohen and his colleagues have taken this idea to the lab, where they have explored the idea that more testosterone in the womb is likely to lead to autism. Just a little extra testosterone, he hypothesized, could be enough to push boys into autism. Some of their research suggests the possibility that this idea could hold water.

At the same time, however, other researchers have explored the question of whether autism may simply be under-diagnosed in girls. They, too, are finding some intriguing results.

At the Kennedy Krieger Institute in Baltimore, for example, researchers are finding that girls with autism are more likely to slip under the radar because they think and behave differently from boys with the disorder:

Girls struggled more with the ability to recognize social cues and interact with others. They had trouble interpreting requests made of them, took things too literally, struggled to understand jokes and couldn't read into people's tone of voice or facial expressions...

On the other hand, boys exhibited much more physical symptoms. They engaged in repetitive behaviors, like turning the wheel of a toy around and around for extended periods, as well as unusual mannerisms such as flapping their hands..

In addition, boys with autism often express fascinations with topics considered "odd" by the general population (e.g., memorizing timetables or lists of statistics) while girls with autism seem to have fairly gender-appropriate fascinations which must be examined closely in order to appear "autistic." For example, a girl with autism might express a fascination with a pop star, pin up his posters, and know everything about his daily routine  -- which appears "normal" to most parents -- but know little or nothing about his music.

Girls with autism also appear to be less likely to act out and more likely to find adaptive behaviors that allow them to function at least semi-successfully in typical settings. For example, rather than showing aggressive or hyperactive behavior (which, of course, is noticed even in preschoolers) girls with autism may withdraw, become passive, or even become depressed. 

Quiet, "shy," or passive girls are culturally acceptable, and quiet girls are rarely picked out as problem children -- especially if they have a relatively high IQ and are capable of functioning in a school setting. As a result, girls on the spectrum may not be identified as such until they reach their teen years and are completely unable to manage the complex social expectations surrounding sexuality, flirting, and romance.

It seems very likely that the number of girls with autism will appear to rise in the next few years as more girls are identified with the disorder. The question of whether those girls were always there, however, may remain open.


Baron-Cohen S1.The extreme male brain theory of autism. Trends Cogn Sci. 2002 Jun 1;6(6):248-254.

DeWeerdt, S. Autism characteristics differ by gender, studies find. Simons Foundation, 27 March 2014.

Dworzynski K. et al. J. Am. Acad. Child Adolesc. Psychiatry 51, 788-797 (2012)

Sarris, M. Not Just for Boys: When Autism Spectrum Disorders Affect Girls. Interactive Autism Network at Kennedy Krieger Institute, February 19, 2013.

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