A number of studies have shown that some parents of children with autism show mild autistic tendencies. This has been called the ‘broader autism phenotype’. However, less is known as to whether such phenomenon also affects typically developing brothers and sisters of children with autism. That is, are non-affected siblings of kids with autism free developmental problems or do they show a broader autism phenotype?

To answer this question a team from the Hebrew University of Jerusalem conducted a large longitudinal study of non-affected siblings of kids with autism. Specifically, the authors examined 37 children (14 girls and 23 boys) with an older brother or sister with autism. These kids were followed for 7 years after birth and were compared to a similar group of siblings of typically developing kids.

By age 7, 40% of the siblings of kids with autism had cognitive, language, or academic problems. This compared to only 16% of the siblings of typically developing kids. The authors then tried to identify the factors that predicted such problems at age 7. It was the kids’ language skills during preschool (and not cognitive skills) that best predicted problems at age 7. That is, those siblings with language difficulties in preschool were more likely to have cognitive, language, or academic problems in middle childhood. These findings underscore the importance of early identification of developmental, and specially language, delays, not only in children with autism but also their siblings. The findings also suggest the presence of a broader autism phenotype among a subgroup of siblings of children with autism.

Gamliel, I., Yirmiya, N., Jaffe, D., Manor, O., & Sigman, M. (2009). Developmental Trajectories in Siblings of Children with Autism: Cognition and Language from 4 Months to 7 Years Journal of Autism and Developmental Disorders DOI: 10.1007/s10803-009-0727-2

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6 Responses to Siblings of kids with autism: 7 years later.

  1. Anonymous says:

    Nestor,

    Its interesting that the older siblings of ASD have early communication problems (40%), as does a large percentage of typically developing kids (16%). Childhood communication disorders are also one of the major factors in diagnostic substitution associated with the 10 fold increase in ASD prevelance subsquent to the publication of DSM-IV.

    The reliability of designs for the ‘Broad Autism Phenotype’ are becoming under increasing scrutiny. Plomin’s group in the UK has applied a questionaire measuring autistic-like traits in the general population by recruiting thousands of twin pairs taken from a twin registry and reported the following:

    the 5% highest scorers were assessed as possessing ‘extreme autistic-like traits’ and “Around 10% of all children showed only social impairment, only communicative difficulties or only rigid and repetitive interests and behavior, and these problems appeared to be at a level of severity comparable to that found in children with diagnosed ASD in our sample” ( Plomin et al 2006 ( MEDLINE ) Plomin et al 2006 page 1218 ( MEDLINE ) ).

    Does 10% of the entire population have an ‘Autism Spectrum Disorder”?

    Japanese schizophrenia researchers applied the Broad Autism Phenotype Questionnaire (BAPQ) to a group of patients diagnosed with either schizophrenia or schizoid personality disorder (A broad schizophrenia phenotype). All participants scored higher than the cutoff points in the BAPQ test.

    Single gene disorders such as Fragile X, and Down’s Syndrome which are associated with ASD and are routinely invoked as evidence that all ASD’s are genetic. Application of these tests to parents of single gene mental retardation with autism have found no eveidence that the BAP is present in unaffected family members.

    All children should be routinely screened for developmental problems, including those with a history of unfavorable events in the pre, peri and nonatal period which are also associated with the ASD’s

  2. hande says:

    When I read this post, the first thing I thought of was that I would have liked to see another group of kids with no siblings compared to these two groups. I am mostly assuming that kids with normal siblings would have had more interaction with the sibling verbally, thus helping their language skills.
    Still, very interesting results.

  3. @Anonymous, thank you for the post. Very interesting points. Also, in this study the results are specific to language problems, not other social-deficits, etc. So the term of “broader autism phenotype” is being stretched a bit to be all-inclusive of any developmental problem.

    @Hande, excellent point. Another option would have been to conduct a similar study with older siblings instead of younger ones. This way, both groups of siblings would be more equivalent.

  4. Anonymous says:

    Doesn’t this study underscore the implications of family stress factors due to having at least one child with ASD? It is well known that disfunction often coincides with the addition of a child with developmental delays. Not to blame the LD child in the slightest, but the amount of difficulties in daily life, school, therapies, sleep disfunction, etc puts extra stressors on all family members. Thus often a negative outcome is that the depleted parents strapped of time, sleep and money often have difficulties in giving non-LD children proper attention. Couldn’t this have more implications to the communication number increase in the ASD sibling group? Not to mention the emotional frustrations the siblings inevitable are overwhelmed with. To me it would appear that this study glosses over other probable reasons to why there are communication problems. I would be interested in the exact study with a group of poverty/lower middle class families vs well to do families with funds for tutoring, extracurricular activities, etc… And, did the study state if the families had only one child with a LD or if some had multiple LD children, which would also complicate the family situation…

    ~JulieL

  5. Thanks Julie for the post. I will check tomorrow on whether the some families had multiple LD children. I think most these valid issues you raise would be addressed by a study using older non-affected siblings. I’ll reply tomorrow with the other information. Thanks, Nestor.

  6. Anonymous says:

    Could you explain to me how reversing the study using older non-affected sibling would address the parental attention and monetary factors? To me inverse application would then create additional factors, particularly the introduced stressor of extra sibling responsibilities. Additionally what diagnostic measures were used for the notation of language skill deficits? Where the children using speech therapy services in preschool?

    ~JulieL

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