Autism Research Sheds New Light on Gender Differences

Jun 11, 2013

Males continue to outnumber females in autism diagnoses, and until recently researchers had almost no insight as to why. Currently, the male-to-female autism ratio is 4-to-1, with an even more startling ratio of 8-to-1 at the higher-functioning end of the autism spectrum.  With an average of one in 88 children (one in 54 boys) living with autism in the U.S., finding an answer to the question of why more boys than girls are diagnosed is quickly becoming more crucial than ever.

A research campaign dedicated to improving the diagnosis and treatment of autism spectrum disorders called the Simons Foundation Autism Research Initiative recently reported findings from the 2013 International Meeting for Autism Research, which showcased exciting research of possible explanations behind the skewed gender ratio in autism diagnoses. Findings from these preliminary studies showed that girls with autism display different brain activity in their response to social cues, and carry more mutations than do boys with autism.

Researcher Stephen Sanders presented preliminary findings from his team’s recent study at the conference, revealing one of the most significant autism research breakthroughs to date.  Results from this Yale University study indicate that the female brain is somehow inherently protected against autism. These results support findings from a twin study published this February in Proceedings of The National Academy of Sciences, which showed that girls who display autism traits are more likely to have siblings with similar traits than boys are. In other words, girls must possess some baseline level of protection, as they generally will not display autism traits unless they possess a variety of risk factors. While the twin study provided strong evidence for the protective effect, it did not address how the protection might work.

Sanders and his team were able to build upon the idea of protective genetic factors in girls by actually observing the variations in genes and mutations between male and female subjects for the first time.  These observations imply that genes, rather than social or environmental factors, are the most likely explanation for the lower rates of autism in girls. “If we can understand why the female brain is inherently protected, then the therapeutic potential would be great,” said Sanders.  

Results from a second study presented by researcher Ami Klin of Emory University support Sanders’ findings that autism differs significantly between boys and girls, not only in development, but in manifestation. One symptomatic gender difference Klin’s team identified is the variation in the way boys and girls engage in their social environments. Surprisingly, girls with milder forms of autism spend a longer amount of time looking at people’s eyes than did girls with more severe autism, with the opposite being true for males. These findings were particularly significant given the small amount of research on girls with autism.

Despite these recent findings, many still question whether girls are actually more protected from autism, or if their symptoms are just more difficult to detect. Some researchers contend that the symptomatic differences may simply be related to diagnostic biases. Either way, there is a clear consensus that while researchers have made significant progress, further studies focused on females living with autism will be essential to understanding the nature of the disorder.

Gaining a deeper understanding of the genetic risk factors related to autism spectrum disorders holds important implications for future developments in treatment. Experts believe that gaining insight into the biology underlying the female protective advantage could greatly aid progress in understanding autism spectrum disorders as a whole and identifying prevention factors. The promising results from the studies presented at the International Meeting for Autism Research bring scientific research one step closer to solving the genetic mystery behind autism, giving hope to families and the medical community alike.