Research articles involving participants with an autism spectrum disorder and published from 2010 through 2012 in Autism, Journal of Autism and Developmental Disorders, Journal of Child Psychology and Child Psychiatry, and Research in Autism Spectrum Disorders were examined to determine the reported gender of participants. The overall male:female ratio was 4.62, which is similar to that reported in epidemiological studies, but the ratio was 6.07 in intervention studies. These findings suggesting that males were in a statistical sense over-represented in intervention studies, but not in other kinds of research. Most (82.21%) of these studies included both male and female participants, but direct comparisons of males and females with an autism spectrum disorder are scarce. Few of the articles we examined, 0.49% of the total, involved only female participants. Roughly half of the articles included comparison groups without an autism spectrum disorder. The percentage of male participants in these comparison groups was substantially and significantly lower than the percentage of males in groups with an autism spectrum disorder, which may in some cases constitute a methodological confound. We encourage researchers to carefully consider the gender of participants as both an extraneous variable and as an independent variable in future investigations.
In 1943, Kanner described eight boys and three girls who exhibited “autistic disturbances of affective contact.” Since that time, epidemiological studies have confirmed that the condition now known as “autism,” and similar conditions which, with autism, constitute “autism spectrum disorders” (ASD), is more common in boys than in girls (see Fombonne, 2003). Although the reported male:female ratio for ASD varied considerably across studies, ranging from 1.33 (McCarthy, Fitzgerald, & Smith, 1984) to 16 (Wing, Yeates, Brierly, & Gould, 1976) in the 29 studies reviewed by Fombonne, the mean male:female ratio was 4.3, which is similar to the 4.6 value evident in 2008 data reported by the 14 sites comprised by the Autism and Developmental Disabilities Monitoring Network (Baio, 2012). Although the exact male:female ratio is impossible to specify, there is good reason to believe that autism “is four to five times more common among boys than girls,” as Autism Speaks (2013) points out on its website.
Edwards, Watkins, Lotfizadeh, and Poling (2012) recently reported on the ages of participants with autism in intervention studies published in Autism, Focus on Autism and other Developmental Disabilities, Journal of Autism and Developmental Disorders (JADD), and Research in Autism Spectrum Disorders (RASD) from 2009 through early 2012 and noted in passing that, “of the 1644 participants whose sex was reported, 85.8% were male” (p. 997). This percentage is equivalent to a male:female ratio of about 6, which suggests that males are in a statistical sense over-represented as participants in intervention studies. It is not clear whether males are similarly over-represented in the literature at large. The purpose of this study was to examine all recent published research articles in four prominent autism journals to provide further information on the gender of people with ASD who serve as research participants.
