Language development among the siblings of children with autistic spectrum disorder.
Preschool siblings of autistic children keep pace with words unless the autistic child also has intellectual disability.
01Research in Context
What this study did
Chuthapisith et al. (2007) tested 54 preschool brothers and sisters of kids with autism. Half of the autistic children also had intellectual disability.
They gave each sibling a short IQ test that measured words and sentences. Then they compared scores to kids who had no autistic brother or sister.
What they found
Most siblings scored right on average. Their word IQ matched the control group.
Only the group whose autistic brother or sister also had intellectual disability scored lower. The drop was small but real.
How this fits with other research
Johnson et al. (2009) saw the same split. When autism is paired with intellectual disability, siblings show more emotional problems, not just lower language.
Meier et al. (2012) followed similar kids to age five. Standard language tests still looked normal, yet natural conversation samples caught subtle social gaps.
Chien et al. (2017) stretched the timeline further. By elementary school these siblings show poorer school attitude and more behavior issues, even when early IQ looked fine.
Why it matters
If your client has both autism and intellectual disability, do not assume the typically developing sibling is "fine." Check their language, mood, and classroom behavior. A quick 10-minute parent chat about the sibling can flag issues early and open the door for support or a referral.
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02At a glance
03Original abstract
Language development in 32 preschool siblings (aged 2-6 years) of children with diagnosed autistic spectrum disorder (ASD) was compared with that of a control group of 28 typical preschool children. Groups were matched by siblings' age, gender, maternal educational level and family income. The mean ages of the siblings group and the control group were 4.2 and 4.4 years. Eight of the siblings had delayed language development, of whom three received a diagnosis of developmental language disorder (DLD) and one of ASD. The sibling with ASD and two of those with DLD were excluded; the remaining 29 siblings and the controls were administered the Stanford-Binet IV. Verbal IQs of siblings were not significantly different from the control group. Siblings of children with ASD associated with intellectual impairment ('mental retardation' (MR) in Thailand) had significantly lower verbal IQ scores than siblings of children with ASD but without MR.
Autism : the international journal of research and practice, 2007 · doi:10.1177/1362361307075706