Autistic behavior in young boys with fragile X syndrome.
Expect a quarter of fragile-X boys to screen positive on CARS, but check real social behavior before labeling severe autism.
01Research in Context
What this study did
Doctors gave the CARS autism screener to 59 boys with fragile X. Ages ranged from 2 to 11. They wanted to know how many boys scored above the autism cutoff.
What they found
One in four boys crossed the autism cutoff. Most were mild or moderate. Higher scores linked to lower developmental age, not family income or child age.
How this fits with other research
Olsson et al. (2001) followed the same boys for three years. They showed that autistic behavior, not fragile-X protein level, predicted slower skill growth.
Casey et al. (2009) later repeated the design with girls. Girls who showed even mild autistic signs also had lower scores over time.
Waldron et al. (2023) looked at preschoolers and found that kids with fragile X still looked at faces more than kids with non-syndromic autism. This warns us: CARS can flag both groups, but the two groups act differently in social settings.
Why it matters
When a boy with fragile X scores high on CARS, plan for extra developmental support. Do not assume severe autism. Watch real social moments: face looking, shared smiles. If these are present, teach play and language first before full ASD protocols.
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02At a glance
03Original abstract
A sample of 57 boys with fragile X syndrome (fraX) between the ages of 24 and 133 months was rated using the Childhood Autism Rating Scale (CARS) to assess the extent to which autism and autistic features were evident in a young population. Fourteen subjects (approximately 25% of the sample) scored above the cutoff for autism, suggesting a relatively high incidence of autistic behavior. All but 2 of these 14 were in the mildly or moderately autistic range, however, and only a few items received severe ratings, suggesting that severe autism is relatively rare in fraX, at least during the early years. The CARS resulted in a continuum of autistic ratings in the fraX population, but no particular items on the CARS contributed disproportionately to autism ratings. A visual comparison of ratings on an autistic, non-fraX sample revealed similar profiles of ratings, suggesting that differentiating fraX and autism on the basis of CARS ratings is not likely. Within the fraX group, chronological age and socioeconomic status did not correlate with CARS ratings, but severity of delay was strongly related, such that more severely delayed children scored higher (more autistic) on the CARS.
Journal of autism and developmental disorders, 1998 · doi:10.1023/a:1026048027397