International Meeting for Autism Research (London, May 15-17, 2008): Developmental Trajectories of Social-Communicative Abilities in Younger Siblings of Children with ASD

Developmental Trajectories of Social-Communicative Abilities in Younger Siblings of Children with ASD

Saturday, May 17, 2008
Champagne Terrace/Bordeaux (Novotel London West)
10:30 AM
E. E. Malesa , Department of Psychology & Human Development, Vanderbilt University, Nashville, TN
J. H. Foss-Feig , Department of Psychology & Human Development, Vanderbilt University, Nashville, TN
C. R. McMahon , Department of Psychology & Human Development, Vanderbilt University, Nashville, TN
T. A. Walden , Department of Psychology & Human Development, Vanderbilt University, Nashville, TN
P. J. Yoder , Department of Special Education, Vanderbilt University, Nashville, TN
W. Stone , Vanderbilt Children's Hospital, Vanderbilt University, Nashville, TN
Background: Younger siblings of children with ASD (SIBS-ASD) are at elevated risk for ASD or autism- related symptomatology, often described as the Broader Autism Phenotype (BAP). Early deficits in social-communicative abilities such as initiating and responding to joint attention (IJA; RJA), functional play, requesting, and imitation have been found in these children at young ages, though little is known about the development of these abilities over time or how they relate to different diagnostic outcomes.
Objectives: To examine the developmental trajectories of social-communicative abilities associated with differential outcome in SIBS-ASD.
Methods: Forty-five SIBS-ASD and 30 younger siblings of typically developing children (SIBS-TD) participated in this study. Children were seen at three time points (mean CAs: T1: 15.6; T2: 19.5 ; T3: 23.5), and were assessed using an RJA task (see Presmanes et al., 2007) and the Screening Tool for Autism in Two-Year Olds (STAT; Stone et al., 2004) from which measures of IJA, requesting, functional play, and imitation were derived. Outcome groups of SIBS-ASD were ASD, BAP, or no ASD concerns (NC), based on ADOS scores and clinical judgment after 24 months of age. A mixed design ANOVA and MANOVA were used to examine changes over time within and between groups.
Results: Results revealed a significant main effect (ME) of Time for RJA (p=.031), Play (p=.004) and IJA (p=.001), and significant ME of Group for RJA (p<.001), Requesting (p=.006), IJA (p=.005), and Imitation (p=.046).  Pairwise group comparisons revealed that the: 1) NC group scored lower than the SIBS-TD on Imitation only; 2) ASD group scored lower than the NC group on RJA, Requesting, and IJA; 3) BAP group’s performance was similar to the ASD group on some tasks and similar to the NC and SIBS-TD groups on others. 
Conclusions: SIBS-ASD with differential outcomes exhibit varying trajectories of social-communicative skills.