Having Older Siblings is Associated with Less Severe Social Communication Symptoms in Young Children with Autism Spectrum Disorder.

Among typically developing children, having sibling relationships promotes the development of social skills. This is a retrospective study of the effect of having sibling/s on the severity of the clinical presentation of autism spectrum disorder (ASD). The study included 112 children, 99 males and 15 females, mean age 29.6 ± 9.2 months, diagnosed with ASD. The study population was composed of a group of children with ASD who had older typically developing sibling/s (n = 56) pair-matched for age and cognitive level to a group of children with ASD without sibling/s. Each participant underwent a comprehensive assessment using standardized tests. The group with older sibling/s had less severe observed social deficits (Autism Diagnostic Observation Schedule-Social Affect calibrated severity scales [ADOS-SA-CSS]) and fewer reported non-verbal communication impairments (Autism Diagnostic Interview-Revised [ADI-R]). Regression analyses revealed that, for the ADOS-SA-CSS, higher cognitive level and having older sibling/s were associated with less severe observed social affect deficits. This model explained 32.0 % of the variance. For the ADI-R communication scores, older age, higher cognitive level and having older sibling/s were associated with less severe reported non-verbal communication impairments. This model explained 33.0 % of the variance. The main finding in this study is that a familial factor, specifically having older sibling/s, was associated with better social communication abilities in children with ASD, in addition to age and cognitive ability. Having sibling/s may offer opportunities for the child with ASD to experience social interactions with children and to acquire communication skills.