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Down syndrome (DS) and autism spectrum disorder (ASD) are two neurodevelopmental disorders characterized by impairments in language. Most studies do not consider the possible role sex differences may play in language profiles. Thus, the current study aimed to evaluate whether parent-reported structural and pragmatic language vary as a function of sex in youth with DS (n = 37), ASD (n = 106), and typical development (TD; n = 61). Findings suggest a female advantage in both structural and pragmatic language in DS; in contrast, no sex differences were found for either ASD or TD. Results suggest that males with DS may require more extensive interventions for language. Future research should investigate how age, IQ, and mode of measurement may impact the nature of these observations. [ABSTRACT FROM AUTHOR]

Executive functioning is thought to contribute to adaptive behavior skills development in individuals with autism spectrum disorder (ASD). However, supporting data are largely based on caregiver reports of executive functioning. The current study evaluated whether performance-based measures of executive functioning (working memory and inhibition) explained unique variance in parent-reported adaptive functioning among youth with ASD without an intellectual disability. Both spatial and verbal working memory were associated with adaptive functioning, particularly communication and daily living skills. Our findings demonstrate a robust relationship between working memory and adaptive functioning that translates across different measurement modalities. This preliminary study highlights that targeting executive functioning may be a critical component of an adaptive function training program. [Additional funding for this research was provided by the Intellectual and Developmental Disabilities Research Center at Children's National Medical Center and the National Institutes of Health General Clinical Research Center.]

Although norm-referenced scores are essential to the identification of disability, they possess several features which affect their sensitivity to change. Norm-referenced scores often decrease over time among people with neurodevelopmental disorders who exhibit slower-than-average increases in ability. Further, the reliability of norm-referenced scores is lower at the tails of the distribution, resulting in floor effects and increased measurement error for people with neurodevelopmental disorders. In contrast, the person ability scores generated during the process of constructing a standardized test with item response theory are designed to assess change. We illustrate these limitations of norm-referenced scores, and relative advantages of ability scores, using data from studies of autism spectrum disorder and creatine transporter deficiency.