Mental Health Problems Among Siblings of Children with Autism

Background:  

As rates of autism spectrum disorder (ASD) diagnoses have risen dramatically over the past 40 years, so has the number of siblings growing up with a brother or sister with ASD.  Despite the recent increase in research on siblings of individuals with ASD, there is no consensus on whether these siblings are at risk for negative outcomes.  Some studies show that siblings exhibit more internalizing and externalizing problems, peer and conduct problems, hyperactivity, delinquent behavior, and withdrawal when compared to siblings of children without ASD.  Others, however, report that siblings of individuals with ASD are well-adjusted and show no more negative outcomes than control groups.  The present study examined patterns and predictors of one negative outcome that may be especially prevalent among siblings of children with ASD – anxiety.

Objectives:  

This study had two objectives: 1) Do siblings of children with ASD have higher rates of anxiety problems relative to a normed sample? and 2) Do characteristics of the parents and of the brother/sister with ASD predict sibling anxiety?

Methods:  

Participants were 1755 siblings of children diagnosed with ASD, who were part of the Simons Simplex Collection.  The siblings ranged in age from 3 – 18 years, with a mean of 9 years.  Sibling anxiety was measured using the anxiety subscale of the Child Behavior Checklist.  Independent variables included measures of behavior problems, IQ, and autism severity of the child with ASD, as well as parental history of psychiatric disorders and parental broader autism phenotype characteristics (collected from both mothers and fathers).

Results:  

As a whole, siblings did not experience higher rates of borderline or clinical anxiety symptoms; 8% of siblings fell above the borderline range compared to 7% in the general population.  Stratification of the sample by gender and age, however, revealed interesting findings.  Although none of the age/gender groups had elevations in anxiety that reached the clinical range, male siblings in middle childhood were twice as likely as would be expected to fall above the borderline cutoff (13.3% of male siblings aged 6-11, compared to 7% in the general population).  Higher levels of sibling anxiety were predicted by maternal and paternal history of anxiety disorders (Bs=.46 for maternal and .36 for paternal, ps < .01), higher maternal pragmatic language (B=.38, p < .001), and more behavior problems in the child with ASD (B = .03 for internalizing problems and .02 for externalizing problems, ps < .001).

Conclusions:

While siblings overall did not show elevated anxiety symptoms, higher rates of sub-clinical anxiety problems among males and siblings in middle childhood are cause for concern.  Discussion will focus on why these siblings might be at higher risk, and will place these findings in the context of the current literature.