By Sarah Johnson.
Comparing the diagnosis between boys and girls with autism spectrum disorder, it has been found that boys are more likely to be diagnosed with ASD than girls. Data collected by The Autism and Developmental Disabilities Monitoring (ADDM) Network, found that boys were 4 times as likely to be identified with ASD than girls1. Boys have had a higher diagnosis rate for a consecutive amount of years. A large Danish study found an 8-to-1 sex ratio for autism in 1995, but that had dropped to 3-to-1 by 2010 2.
The reason behind the diagnosis has no set answer, however, many believe that it has to deal with doctors not noticing the signs as easily in girls. Since it’s harder to notice signs of autism in girls, studies found that girls receive autism diagnoses later in life than boys 2. Since autism is on a spectrum, signs and conditions vary from diagnosis to diagnosis. Studies are now trying to analyze what symptoms in girls are so different that they go unnoticed.
When looking at early signs between boys vs. girls, it’s found that autism looks different in girls than it does in boys. In society, girls have less restricted interests and behaviors than boys do. Girls are more likely to copy their neurotypical peers that mask their signs of autism than boys do. All of these reasons are why doctors have a hard time detecting signs of autism in girls.
Studies are also being conducted to see how biology affects the differences in ASD diagnosis by sex. The involvement between genetics and autism is very new information. It’s been found that autism spectrum disorders are 80% reliant on inherited genes3. That being said, genes and biology play a major role in understanding trends among diagnoses.
The biological difference behind the diagnosis (boys vs girls) is found in the brain. A gene expansion on the X chromosome called the FMR1 leads to intellectual disability and autism in a boy, which may not produce these symptoms in a girl who has a second intact copy of the gene4.
The more that scientists and doctors are able to understand and study autism, the more they will be able to understand differences in statistics (sex, demographics, ect).
To learn more about autism and early signs please visit the CDC website.
1 Maenner MJ, Shaw KA, Baio J, et al. Prevalence of Autism Spectrum Disorder Among Children Aged 8 Years — Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2016. MMWR Surveill Summ 2020;69 (No. SS-4):1–12. DOI: http://dx.doi.org/10.15585/mmwr.ss6904a1external icon.
2 Jensen CM, Steinhausen HC, Lauritsen MB. Time trends over 16 years in incidence-rates of autism spectrum disorders across the lifespan based on nationwide Danish register data. J Autism Dev Disord. 2014 Aug;44(8):1808-18. doi: 10.1007/s10803-014-2053-6. PMID: 24554161.
3 Bai D, Yip BHK, Windham GC, et al. Association of Genetic and Environmental Factors With Autism in a 5-Country Cohort. JAMA Psychiatry. 2019;76(10):1035–1043. doi:10.1001/jamapsychiatry.2019.1411
4 Gaugler T, Klei L, Sanders SJ, Bodea CA, Goldberg AP, Lee AB, Mahajan M, Manaa D, Pawitan Y, Reichert J, Ripke S, Sandin S, Sklar P, Svantesson O, Reichenberg A, Hultman CM, Devlin B, Roeder K, Buxbaum JD. Most genetic risk for autism resides with common variation. Nat Genet. 2014 Aug;46(8):881-5. doi: 10.1038/ng.3039. Epub 2014 Jul 20. PMID: 25038753; PMCID: PMC4137411.