Minimal Risk of Internalizing Problems in Typically-Developing Siblings of Children with HFASD

Background:  There is a paucity of research on internalizing difficulties of siblings of children with high-functioning autism spectrum disorder (HFASD).  Reviews describe a limited and conflicted field of findings (Meaden et al., 2010; Orsmond & Setzer, 2007) for research on siblings of children on the autism spectrum across the range of functional levels.  Only three studies of internalizing problems in TD siblings of children with HFASD are available and these are limited in quality.  Specifically, all three available studies (Verté, Roeyers, & Buysse, 2003; Ross & Cuskelly, 2006; Rao & Beidel, 2009) used only parent report information from the CBCL.  If sibling depression and anxiety are clinically elevated, developing interventions and increasing focus on these children would become a priority for community and school-based mental health providers.

Objectives:  This group comparison study examined (1) symptom level differences in anxiety and depression between TD siblings of children with HFASD and TD siblings of children with TD siblings and (2) source differences between parent-rated and child self-reported anxiety and depression across these groups. 

Methods:  Eighty-four children, ages 6-16 were participants in the study.  Within the total sample were two groups: 42 TD siblings of children with HFASD and 42 TD siblings of TD children.  Participating TD siblings were matched on age, gender, and ethnicity.  Groups were equivalent on parent education. The TD siblings from both groups had no identified developmental, psychiatric, or educational conditions other than anxiety or depression.  The HFASD reference siblings had to have a WISC-IV short-form IQ > 70, VCI or PRI factor score > 80 and an independent diagnosis of ASD from a licensed physician or psychologist.  A majority of reference siblings (33, 78.6%) also had ADI-R confirmation of the diagnosis.  The Behavior Assessment System for Children-2 (BASC-2; Anxiety and Depression clinical scales), parent (PRS) and child report (SRP) were collected.  Siblings of reference children with HFASD were recruited from a pool of families participating in psychosocial interventions for their sibling with HFASD.  TD siblings of TD children were recruited through public advertisement.  

Results:  Comparison of TD siblings of children with HFASD to TD siblings of TD children indicated no significant multivariate effect between groups for parent-reported internalizing problems (Wilk’s λ = 0.997, F[1,82] = 0.119, p = 0.888) or self-reported internalizing problems (Wilk’s λ = 0.982, F[1,82] = 0.724, p = 0.488).  Source differences indicated no within-group (parent vs. self) multivariate effect for siblings of HFASD children (Wilk’s λ = 0.980, F[1,82] = 0.829, p = 0.440) or siblings of TD children (Wilk’s λ = 0.992, F[1,82] = 0.336, p = 0.715).

Conclusions:  The current study did not support an increased risk of internalizing problems (anxiety and depression) in the TD siblings of children with HFASD.  This is strengthened by consistent levels of internalizing problems by source.  The current result does not support a higher risk of internalizing symptoms for siblings of children with HFASD, though clinicians should maintain awareness of these children and attend to clinical warning signs if presented.