Reliable and valid intellectual assessment is of particular importance when evaluating for an autism spectrum disorder (ASD) because of the need to interpret symptoms within the context of the individual’s developmental level. In addition, cognitive evaluation is important when selecting teaching strategies, developing teaching objectives, and may be the most important prognostic indicator in this population. However, ASD’s impact on cognition is highly variable and, when combined with the interfering behaviors associated with ASD, standardized assessment in this population can be challenging.
The majority of children with ASD exhibit significant scatter of scores on cognitive profiles, rendering the obtained composite scores non-unitary and potentially invalid. Research suggests that that over 50% of children/adolescents with ASD have significant discrepancies between their verbal intelligence quotient (VIQ) and their non-verbal intelligence quotient (NVIQ); a substantially higher rate than in the normative samples on which intellectual measures are standardized. General recommendations regarding test selection include choosing an instrument with reduced verbal loading, opportunities for teaching, decreased demands for social engagement, few timed tasks, and hands-on activities. The Differential Ability Scale--Second Edition (DAS-II; Elliott, 2007) is one instrument specifically recommended for use with this population; however, given its relatively recent publication, there is minimal published research on its use in general and special populations. In particular, there are no extant data describing the performance of children/adolescents with ASD on the DAS-II.
Objectives:
The objective of the proposed study is to examine the clinical utility and profile variability of the DAS-II in a large, well characterized sample of children/adolescents with ASD.
Methods:
Data will be analyzed for children with ASD who participated in the Simons Simplex Collection (SSC). The SSC is a repository of clinical and genetic data from families with only one child (between the ages of 4 and 18) with an ASD (i.e., simplex families). All probands included in the SSC met diagnostic criteria for ASD based on research-reliable administrations of the ADI-R and ADOS and in clinical opinion. Only probands who obtained standard scores on all subtests on either the DAS-II Early Years (EY; N=887) or the DAS-II School Age (SA; N=870) will be included in the sample.
Results:
Mean scores at the subtest, cluster, and composite levels for both the DAS-II EY and the DAS-II SA groups will be presented and compared to the normative sample using multivariate or univariate analysis. Proportion of the sample with VIQ/NVIQ discrepancies will be calculated and compared to the normative sample. Within-group comparison will also be made at the subtest level to determine the proportion of the sample with non-unitary VIQ and NVIQ cluster scores.
Conclusions:
In addition to demonstrating the clinical utility of the DAS-II in a population of children with ASD, it is hypothesized that findings from this study will add to the existing literature regarding cognitive profile variability among children with ASD and further emphasize the importance of considering profile variability both at the individual level (i.e., selecting appropriate interventions) and group level (i.e., when defining samples for research).
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