Symptoms of Autism Spectrum Disorder in Children With Down Syndrome and Williams Syndrome.
Kids with Down or Williams syndrome often screen positive for autism, especially in repetitive behaviors, and low IQ alone does not explain it.
01Research in Context
What this study did
The team asked parents to fill out the Social Communication Questionnaire.
They compared kids with Down syndrome, kids with Williams syndrome, and kids from the general population.
The goal was to see how many autism-like behaviors each group showed.
What they found
Both Down and Williams groups scored higher than typical kids.
The biggest gap was in odd, repetitive behaviors like hand flapping or lining up toys.
Low daily-living skills did not fully explain the high scores.
How this fits with other research
Sasson et al. (2022) dug deeper into Down syndrome alone.
They found three clear patterns: low, mixed, and high autism symptoms.
This extends the 2021 finding by showing that "high scores" are not one big blob—there are sub-groups.
Vassos et al. (2016) seems to disagree at first glance.
They reported no difference in stimulus over-selectivity between autism, Down syndrome, and typical kids.
The key difference is matching: V et al. matched groups by mental age, while Higgins et al. (2021) used broad population samples.
When IQ is held constant, differences shrink; when it is not, Down and Williams kids look more autistic.
Why it matters
If you test a child with Down or Williams syndrome, expect SCQ scores above the usual cut-off.
Do not dismiss the numbers as "just low IQ."
Look at repetitive and sensory behaviors first—they pop out the most.
Use the Sasson et al. (2022) profiles to decide who needs a full ADOS and who needs sleep or medical checks instead.
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02At a glance
03Original abstract
Research suggests that people with a Williams syndrome (WS) or Down syndrome (DS) diagnosis display an increased prevalence of autism spectrum disorder (ASD) when compared to the general population. This study aimed to examine characteristics of ASD in a group of children with DS or WS. Results suggest that children with DS and WS exhibit higher levels of autism symptoms than the general population, particularly in the area of unusual behaviors, and that these elevations are not solely due to deficits in adaptive behavior. There are many possible explanations for these elevations, such as issues with measurement, etiological overlap, or similar behavioral phenotypes. More research is needed to further our understanding of the overlap of ASD symptoms in these populations.
American journal on intellectual and developmental disabilities, 2021 · doi:10.1352/1944-7558-126.1.58