Are autism spectrum disorders comparable in boys and girls? An examination of sex differences in behaviour, cognition and psychopathology in a predominantly low functioning sample

- Background: The female autism spectrum disorder (ASD) phenotype is currently underresearched. Girls with ASD may differ from boys with ASD, yet few studies have tested this hypothesis, particularly among low functioning individuals. This study compared girls and boys with predominantly low functioning ASD and typically developing girls during middle and late childhood across autism symptoms, cognition, sensory overresponsivity, and co-occurring psychopathology. - Methods: Three mental-age–matched groups were compared: girls with ASD (N = 27), boys with ASD (N = 27), and typically developing girls (N = 17). Their ages ranged from 7 to 19 years old. The majority of individuals in the ASD sample had an intelligence quotient of less than 70. Participants were assessed on standard social cognition and attention to detail tasks. Parents completed behavior questionnaires. - Results: Mean levels of autism symptoms were not significantly different for boys and girls with ASD, and they were significantly higher than those of typically developing girls. There were some weak trends for boys with ASD to show more compulsive behavior, inattention/hyperactivity and taste sensory overresponsivity than girls with ASD, but differences were not significant after controlling for multiple comparisons. The Block Design task, assessing attention to detail, showed a significant sex difference, with boys with ASD outperforming both girls with ASD and typically developing girls. - Conclusions: Predominantly low functioning girls with ASD differed from typically developing girls but did not differ from boys with ASD with regard to their levels of autism symptoms, sensory overresponsivity, or co-occurring psychopathology. These data feed into debates about whether ASD assessment tools require sex-specific criteria and to what degree treatment should be tailored to the sex of the individual