Autism spectrum disorder in fragile X syndrome: Communication, social interaction, and specific behaviors

Authors

  • Walter E. Kaufmann,

    Corresponding author
    1. Kennedy Krieger Institute, Baltimore, Maryland
    2. Departments of Pathology and Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
    3. Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
    4. Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
    5. Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
    • Kennedy Krieger Institute, 3901 Greenspring Avenue, Room 208, Baltimore, MD 21211.
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  • Ranon Cortell,

    1. Kennedy Krieger Institute, Baltimore, Maryland
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  • Alice S.M. Kau,

    1. Kennedy Krieger Institute, Baltimore, Maryland
    Current affiliation:
    1. Mental Retardation and Developmental Disabilities Branch, National Institute of Child Health and Human Development, Bethesda, MD.
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  • Irena Bukelis,

    1. Kennedy Krieger Institute, Baltimore, Maryland
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  • Elaine Tierney,

    1. Kennedy Krieger Institute, Baltimore, Maryland
    2. Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
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  • Robert M. Gray,

    1. Kennedy Krieger Institute, Baltimore, Maryland
    2. Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
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  • Christiane Cox,

    1. Kennedy Krieger Institute, Baltimore, Maryland
    2. Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
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  • George T. Capone,

    1. Kennedy Krieger Institute, Baltimore, Maryland
    2. Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
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  • Pia Stanard

    1. Kennedy Krieger Institute, Baltimore, Maryland
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Abstract

The present study extends our previous work on social behavior impairment in young males with fragile X syndrome (FraX). Specifically, we evaluated whether the autistic phenomenon in FraX is expressed as a range of behavioral impairments as in idiopathic autism (Aut). We also examined whether there are behaviors, identified as items of the Autism Diagnostic Interview-Revised (ADI-R), that in FraX predispose to or differentiate subjects with autism spectrum disorder (ASD) diagnosis. Finally, regression models were utilized to test the relative contribution of reduced communication and socialization skills to ADI-R scores and diagnoses. A cohort of 56 boys (3–8 years) with FraX was examined in terms of scores on measures of cognition (IQ was a co-variate in most analyses.), autistic behavior, problem/aberrant behavior, adaptive behavior, and language development. We found that, indeed, in terms of problem behavior and adaptive skills, there is a range of severity from FraX + Aut to FraX + PDD (Pervasive Developmental Disorder) to FraX + none. ADI-R items representing “Play” types of interaction appear to be “susceptibility” factors since they were abnormal across the FraX cohort. Integrated regression models demonstrated that items reflecting complex social interaction differentiated the FraX + ASD (Aut + PDD) subgroup from the rest of the FraX cohort, while abnormalities in basic verbal and non-verbal communication distinguished the most severely affected boys with FraX + Aut from the milder FraX + PDD cohort. Models incorporating language, adaptive communication, and adaptive socialization skills revealed that socialization was not only the main influence on scores but also a predictor of ASD diagnosis. Altogether, our findings demonstrate that the diagnosis of ASD in FraX reflects, to a large extent, an impairment in social interaction that is expressed with variable severity in young males with FraX. © 2004 Wiley-Liss, Inc.

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