Examining the Relationship Between Varying Symptom Presentation in Children with Autism Spectrum Disorder and the Adjustment of Their Typically Developing Siblings

Background: Sibling relationships are known to have a significant impact on the process of social and emotional development (Dunn, 2008). A number of studies have focused on potential challenges faced by typically developing (TD) siblings of children who have physical or developmental disability, including autism spectrum disorder (ASD) (Bagenholm & Gillberg, 1991; Knott, Lewis & Williams, 1995; Opperman & Alant, 2003; Hastings, 2007; Barr, McLeod & Daniel, 2008). This study aims to examine how the varying symptom presentation in children with ASD impacts the adjustment of their TD siblings. Objectives: Assess the relationship between the behavioral phenotype and severity of symptoms in children with ASD and the social, emotional and behavioral adjustment of their unaffected siblings. Methods: A convenience sample of 99 families drawn from a larger study who have a child aged 4 to 18, affected with ASD, as well as a TD child aged 6 to 23, have participated in this study. To verify ASD diagnosis in the proband, the Autism Diagnostic Observation Schedule (ADOS) and Autism Diagnostic Interview-Revised (ADI-R), were performed. In addition, cognitive, adaptive and behavioral measures were administered. Overall severity of symptoms was calculated using the Calibrated Severity Score (CSS) (Gotham, Pickles & Lord, 2009). To confirm neurotypical development in the unaffected child, parents were asked to complete the Social Responsiveness Scale (SRS) and to provide medical and educational information. In addition, parents completed measures to characterize emotional and behavioral development of their TD child, including subdomains of the Child Behavior Checklist (CBCL), and the Maladaptive Behavior Index (MBI) of the Vineland Adaptive Behavioral Scales-II (VABS-II). Results: A regression analysis was used to test for associations between proband behavioral phenotype and TD siblings' emotional, and behavioral development. When compared to the Restricted and Repetitive Behaviors and Interests (RRBI) domain on the ADI-R, ten of the fifteen subdomains in TD siblings tested on the VABS-II MBI and CBCL were found to be statistically significant (p < .05): VABS-II Internalizing, CBCL Social Problems, CBCL Aggressive Behavior, CBCL Anxious/Depressed, CBCL Internalizing Problems, CBCL Attention Problems, CBCL Affective Problems, CBCL Somatic Complaints, CBCL Anxiety Problems, CBCL Oppositional Defiant. All other domains on the ADOS and ADI-R, including those assessing social interaction and communication deficits, as well as CSS, were not associated with difficulties in TD siblings. Conclusions: Children with ASD who have an increased presence of RRBIs have siblings with a higher prevalence of social, emotional and behavioral difficulties, when measured using subscales on the CBCL and VABS-II MBI. Social interaction and communication domains on the ADI-R and ADOS, as well as CSS were not significantly correlated with difficulties in the TD sibling. As this study was hypothesis-generating, future studies will be needed to further clarify the relationship between RRBIs and their effects on TD sibling development.