Exploring sex differences in the manifestation of autistic traits in young children

Abstract Background Previous works attempting to document sex differences in younger children with autism spectrum disorder (ASD) have yielded inconsistent results. Therefore, this study aimed to investigate potential sex differences in the manifestation of ASD-related features in toddlers and preschoolers with ASD, typical development (TD), and other developmental disorders (OD). Method Analyses were conducted using a sample of 557 young children, aged 18−42 months, composed of 261 participants with ASD (n = 207 males; n = 54 females), 223 TD (n = 133 males; n = 90 females), and 73 with OD (n = 45 males; n = 28 females). A battery of tests, including the gold standard ASD diagnostic assessments and caregiver questionnaires, were used to measure symptomatology. We implemented ANCOVA while covarying for adaptive skills to detect sex differences in ASD trait presentation. Results The ASD group demonstrated significant differences in the parent-report social interaction domain with more deficits in females than males, while the TD and OD groups found that males exhibited more restricted or repetitive behaviors (RRB) than females. When the participants were limited to children over 24 months to ensure good diagnostic validity, the same patterns in traits by sex were observed, except in the OD group, suggesting that the younger children might have driven the significant findings. Conclusion Sex differences in the social interaction domain were reported by parents of children with ASD, while children in the non-ASD groups exhibited differences in RRBs. Therefore, healthcare professionals should become aware of the different presentational profiles in young children to prevent over or under detection of ASD.