The Impact of Siblings on the Clinical Presentation of Children with Autism Spectrum Disorders

Background:

Sibling relationships may influence a child’s development through close interaction, role-playing and sharing of emotions and experiences. These relationships might affect the younger and the older siblings differently. It is well accepted that older siblings may influence their younger siblings’ development by serving as role models. Previous studies reported that positive sibling relationships may facilitate social development of children with autism spectrum disorders (ASD).

 Objectives:  The current study examined the impact of younger/older siblings on the clinical presentation of children with ASD.

 Methods:  

The study included 528 participants, 462 boys and 66 girls, with ages ranging from 18 to 60 months (M=33.1m, SD=11.1), diagnosed with ASD. Data regarding the number of siblings and their order in the family was obtained from the parents. Of the entire ASD group, 145 participants did not have a sibling, 116 had one or more, younger siblings, 215 had one or more, older siblings, and 52 had both younger and older siblings. The participants underwent assessments of autism severity, cognitive ability and adaptive skills. Autism symptoms severity was measured using the ADOS social-affect (SA) and restrictive and repetitive behaviors calibrated severity scales, and ADI-R algorithm scores in all domains. Level of adaptive skills was measured using the Vineland Adaptive Behavior Scales (VABS) composite standard scores.

Results:  

Regarding autism symptoms severity, the ADOS SA severity scores were significantly lower in the ASD group with siblings in comparison to the group without siblings (p=.01). No significant differences were noted between the groups in ADOS RRB severity scores. In the same direction, parental report using the ADI-R algorithm scores revealed significantly lower scores in the communication domain for the group with siblings in comparison to the group without siblings (P=.001). No significant differences between the examined groups were noted in adaptive behaviors. We then examined the impact of the sibling order, older or younger than the index child, on the clinical presentation. The ADOS SA severity scores were significantly lower in the subgroup with only older sibling(s) (P=.003) and in the subgroup with only younger sibling(s) (P=.001) than in the group without siblings. In the same direction, the ADI-R algorithm scores were significantly lower in the communication domain for the subgroup with only older siblings (P=.002), and in the social and communication domains for the subgroup with only younger siblings (P=.013) than in the group without any siblings. The VABS composite scores were significantly higher only for the subgroup with younger siblings, but not for the subgroup with older siblings than for the group without siblings (P=.05). The positive effect of having either older or younger siblings on autism severity and adaptive skills disappeared in the subgroup with both older and younger siblings.

Conclusions:  

For children with ASD, having either younger or older siblings may encourage social engagement with the sibling and may translate into better social interaction, communication and adaptive skills. Future studies should look at other siblings' characteristics beyond age, such as gender and social abilities that might affect the clinical presentation in ASD.