Social-Communicative Abilities In Young Siblings of Children with Autism Spectrum Disorder (ASD)

Background:  Previous research shows that the prevalence of social and communicative impairments in siblings of children with ASD is higher than in children without a family member with ASD, which points to a broad ASD-phenotype (e.g. Constantino et al., 2006). Joint attention which is one of the earliest markers for autism, also seems to be impaired in young siblings of children with ASD. However, results are somewhat mixed as to what forms of joint attention are impaired.  (Cassel et al., 2007; Goldberg et al., 2005)

Objectives:  The aim of the present study is to replicate previous findings, which show  more symptoms of ASD and less joint attention in siblings of children with ASD.

Methods:  Data were collected from 18 siblings of children with ASD and 22 typically developing controls  at the age of 18 months. The Autism Diagnostic Observation Schedule-Generic (ADOS-G; Lord et al., 1989) was administered to assess symptoms of autism. The abridged version of the Early Social Communicative Scales (ESCS; Mundy & Hogan, 1996) was used to asses initiating joint attention (IJA), responding to joint attention (RJA) and initiating behavior request (IBR). A second measure for IJA was the infants’ reaction to an unexpected positive event. The results for IJA were based on the average of the two measures.

Results:  Siblings of children with ASD score higher on the ADOS ,t(38)= -2.1, p<0.05, which shows that they have more social-communicative symptoms of ASD than the controls. There is no difference between the groups in initiation or response to joint attention. There is a difference in requesting, but only in the low level behavior use of eye contact to request: siblings of children with ASD use less eye contact to request, t(38)=2.4, p<0.05.

Conclusions:  The 18-month old siblings seem to share some characteristics with their older brothers and sisters with ASD as is shown in the higher score on the ADOS. However, the deficit in joint attention is less clear than in previous research. Follow-up of this sample will reveal to what extent the scores at 18 months are predictive for autism symptomatology and further development of joint attention skills.