Girls with autistic spectrum disorders (ASD) show less severe repetitive/restricted behaviours (RRBs) than boys, according to new research from Stanford University School of Medicine.
The study, which appeared in the journal Molecular Autism, analysed symptom severity in a sample of 128 ASD girls and 614 age- and IQ-matched ASD boys. The researchers found ‘robust evidence’ for reduced levels of RRBs in girls, compared to boys, with ASD, providing ‘the strongest evidence to date for sex differences in a core phenotypic feature of childhood ASD.’
As RRBs are the most overt and noticeable feature of ASD the study raises the possibility that, ‘girls with less prominent RRB may miss being tested for ASD or get misclassified as having social communication disorder.’ But it also warns that, ‘boys with more pronounced RRB may show more false positives for ASD, given that repetitive/restricted behaviors are not specific to children with ASD and are also observed in other neurodevelopmental disorders.’
‘Regardless of the potential impact on diagnosis, our findings point to a need for further research on the development of clinical instruments that are better tailored towards autism in females,’ the authors say.
The study also linked the behavioural difference to brain structure by analysing differences in a well-matched group of 25 ASD girls, 25 ASD boys, 19 typically developing (TD) girls, and 19 TD boys. It concludes: ‘Our findings indicate that the brains of girls with ASD are structured differently from those of boys and that some of these differences are linked to sex differences in behavioral impairments.’