1. To investigate the effect of having non-ASD sibling/s on autism symptoms severity of the child with ASD.
2. To examine the impact of having older or younger non-ASD sibling/s on autism symptoms severity of the ASD probands
Sibling relationships may influence a child’s development through close interaction, role-playing and sharing of emotions and experiences. Only a few studies have examined outcomes for the sibling with ASD. As with TD children, sibling interactions reportedly have influence on the prosocial development of the child with ASD reflected in better adaptive social skills.
The study included 533 participants (466 males, 67 females) diagnosed with ASD, with age range of 18-60 months and a mean age of 33.2m.±11.2. Evaluation included, medical, developmental and familial histories, including number of siblings, their ages and medical and developmental histories. Autism symptoms severity was assessed using the Autism Diagnostic Observation Scales Social Affect Calibrated Severity Scores (ADOS-SACSS), ADOS Repetitive Restricted Behaviors (RRB CSS) and Autism Diagnosis Interview-Revised (ADI-R) in social, communication and RRB domains. Adaptive skills were measured using the Vineland Adaptive Behavior Scales (VABS).
In both autism severity measures, the ADOS SA-CSS and the ADI-R communication scores, the group with sibling/s showed lower scores in comparison to the group without siblings. Having either only older sibling/s or only younger sibling/s was associated with significantly less severe observed social deficits and reported communication deficits. However, in families with both older sibling/s and younger sibling/s, the effect of having sibling/s on autism severity disappeared.
Using a regression model analysis revealed that older child’s age, higher VABS scores and having older sibling/s were associated with lower ADOS-SA CSS scores.
For the child with ASD, having sibling/s may offer opportunities for learning basic communication skills (gestures, pointing, play, verbal production) through imitation and interaction.