Interactions Between Children with Autism Spectrum Disorder and Their Younger Sibling

Background: Due to the complementary and reciprocal nature of sibling interactions, siblings play a unique socialization function in the early development. Research however suggests that interactions between young infants and their older sibling with autism spectrum disorder (ASD) differ from those in which no child with ASD is involved. Given that siblings of children with ASD have an increased risk of developing ASD or subclinical features of ASD (Broader Autism Phenotype), early sibling interactions may be especially important for them. 

Objectives: The aim was to explore differences in early sibling interactions between high-risk infants and a low-risk control group. Additionally, social-communicative characteristics of both children were taken into account. 

Methods:  Sibling interactions between 18-month-old infants and their older sibling (21 high-risk dyads and 29 low-risk dyads) were observed and videotaped during a play observation at home. Frequencies and/or durations of interactive behaviour (initiation-response, interaction with each other/experimenter/parent) and non-interactive behaviour (orientation toward sibling, doing nothing, solitary play, repetitive/stereotyped behaviour, distress) were coded. Social-communicative skills were examined using the ADOS2 and the Social Responsiveness Scale. 

Results: Preliminary analyses in a subsample show that children with ASD tended to use more negative initiations than older typically developing children (U=65; p=.071). Second, in the control group, older children took a more dominant role (more positive (Z=-3.30, p<.001) and negative (Z=-4.51, p<.001) initiations than their younger sibling) while younger children followed their lead (more positive (Z=-4.50, p<.001) and negative (Z=-2.38, p=.016) responses). In the high-risk group, only the negative initiations were significantly more prevalent in older siblings with ASD (Z=-2.12, p=.047).

In both groups, we found positive correlations between the number of initiations of the youngest/oldest child and the number of responses of the oldest/youngest child (range r: .53 to .83). These higher levels of initiations and responses were positively correlated with mutual shared attention (range r: .43 to .94). In the high-risk group, social difficulties of the child with ASD were positively correlated with the youngest child’s positive initiations (r=.58). Furthermore, we found that interactive behaviour of the youngest child at 18 months (positive initiations, responses) was negatively associated with social difficulties (ADOS) at 24 months (range r: -.53 to -.63). More elaborate analyses on the whole sample will be presented at the conference.

Conclusions:  The current study confirms that interactions between young infants and their older sibling with ASD differ significantly from interactions between young infants and their older typically developing sibling. While in typical development roles are more asymmetric and reciprocal (e.g., teacher and learner), younger siblings of children with ASD seem to compensate more for the social difficulties of their older brother/sister. In addition, younger siblings of children with ASD who were more interactive with their brother/sister at 18 months showed better social-communicative abilities at 24 months.