Kanne, Gerber, Quirmbach, Sparrow, Cicchetti, Saulnier (2011)

Title

The Role of Adaptive Behavior in Autism Spectrum Disorders: Implications for Functional Outcome

Citation

Kanne, S.M., Gerber, A.J., Quirmbach, L.M., Sparrow, S.S., Cicchetti, D.V., Saulnier, C.A. (2011). The role of adaptive behavior in autism spectrum disorders: Implications for functional outcome. Journal of Autism and Developmental Disorders, 41(8), 1007-1018. https://doi.org/10.1007/s10803-010-1126-4

Abstract

The relationship between adaptive functioning and autism symptomatology was examined in 1,089 verbal youths with ASD examining results on Vineland-II, IQ, and measures of ASD severity. Strong positive relationships were found between Vineland subscales and IQ. Vineland Composite was negatively associated with age. IQ accounted for a significant amount of the variance in overall adaptive skills (55%) beyond age and ASD severity. Individuals with ASD demonstrated significant adaptive deficits and negligible associations were found between the level of autism symptomatology and adaptive behavior. The results indicate that IQ is a strong predictor of adaptive behavior, the gap between IQ and adaptive impairments decreases in lower-functioning individuals with ASD, and older individuals have a greater gap between IQ and adaptive skills.

Focus of Article

The relationship between Autism Symptom Severity and Adaptive Functioning was the focus of Kanne et al. (2011). This relationship was explored through the testing of 1,089 children (ages 4 to 17) with functional language skills, diagnosed with Autism Spectrum Disorder (ASD) using a variety of assessments (Vineland-II, Autism Diagnostic Interview-Revised (ADI-R), Autism Diagnostic Observation Schedule (ADOS), and Social Responsiveness Scale (SRS), and measures of their individual IQ and severity of ASD. This was deemed socially significant because a previous longitudinal study from 2009 found adults with average IQ scores or near-average cognitive abilities, which found that over 20 years adaptive skills were more highly associated with adult success than IQ, which did not show support of cognitive factors that correlate to adult success. Additionally, the Vineland was the primary focus of the results of this exploration, in part because of its strong positive relationship with IQ, while also providing a standardized score for communication, daily living, social, and motor skills, while assessing a person from birth to adulthood.

How ADOS Differs From ADI-R

The ADOS and ADI-R are both semi-structured assessments that differ in two primary ways. First, The ADOS is a direct assessment that observes the participant, while the ADI-R is an indirect assessment that utilizes parent interviews to assess the participant. Second, while both assessments examine the participant’s communication skills, social interaction skills, and stereotyped and restrictive behaviors, the ADI-R does this through a 93-item/question interview that asks parents to answer based on a scale from 0 to 3; and the ADOS does this through 4 modules (observations) that each focus on a different area, and each have a different number of items to score using different algorithms; however, only Modules 1 – 3 were used within this study. Additionally, but less importantly, the ADOS also examines the participant’s imagination and creativity. Lastly, both had high interrater reliability, but the ADI-R’s was higher.

Authors’ Findings and What May Be Responsible

The WISC-IV indicates the overall intellectual ability (functioning) of a child via their Full-Scale Intelligence Quotient (FSIQ), based on their measures of Verbal Comprehension, Perceptual Reasoning, Processing Speed, and Working Memory. The ADOS and ADI-R assess the participant’s communication & social interaction skills and stereotyped & restrictive behaviors. Two of the four stated purposes (expectations) of this study included confirmation of minimal relationships between Autism Symptom Severity and adaptive behavior regardless of the participant’s age of cognitive levels and examination of the differences between adaptive behavior and cognitive skills, with the assumption of correlation between an increase in cognitive potential and an increase in in the gap between adaptive skills levels and IQ.

Results of the study showed a poor association between adaptive behavior and autism symptom severity, confirming the hypothesis that they are independent from each other. However, the association was stronger with parent-reported assessments, such as the ADI-R, compared to the ADOS which uses direct observation.  Additionally, ADI-R and ADOS scores met the criteria for autism despite the individuals having average IQ’s, leading the authors to question the merits of a diagnosis of autism, stating that rates have decreased in regard to those diagnosed with autism also having a diagnosis of intellectual disability, some criteria that rule out autism are more common in lower-functioning (lower IQ) individuals, and/or autism may reside in a genetic variance that allows for a diagnosis in individuals with higher IQ’s.

Lastly, the study found a strong association between adaptive behavior and IQ, however, the gap between IQ and adaptive skills decreased, rather than the expected increase. IQ scores in the range of having an intellectual disability (WISC-IV FSIQ score below 70) were shown to have strong adaptive skills in relation to an individual’s IQ. The authors noted these findings were consistent with recent research but inconsistent with older research, and that the gap between IQ and adaptive skills widened with age, being greater in older individuals and lesser in younger individuals, but in order to corroborate this, a longitudinal study would need to be conducted. Aspects of inclusions and exclusion criteria that may have affected the findings of the study include, using a large and specific population that may not generalize to other populations, not including non-verbal participants, and not using more specific adaptive skill and IQ criteria. However, the authors’ use of a population that doesn’t exclude IQ levels or autism severity should allow for a greater understanding of autism in regard to the focus of treatments.

Table 1

Table 2

Assessment Descriptions

• Autism Diagnostic Interview-Revised (ADI-R)
  The ADI-R yields scores in the areas of reciprocal social interaction, language/communication, and restricted, repetitive, and stereotyped patterns of behavior.
• Autism Diagnostic Observation Schedule (ADOS)
  The ADOS (Lord et al. 2002) is a semi-structured, standardized assessment which assesses an individual’s behavior in the areas of communication, reciprocal social interaction, imagination/creativity, stereotyped behaviors, and restricted interests.
• Differential Ability Scales, 2nd Edition (DAS-II)
  The DAS-II (Elliot 2007) has 20 cognitive subtests that assess conceptual and reasoning abilities with both pre-school and school-age versions, for ages 30 months to 17 years of age.
• Social Responsiveness Scale (SRS)
  The SRS (Constantino and Todd 2000) is a 65-item parent and teacher report measure assessing autistic traits.
• Vineland Adaptive Behaviors Scales, 2nd Edition (Vineland-II)
  The Vineland-II (Sparrow et al. 2005) assesses individuals from birth to adulthood in their functional personal and social abilities. The Vineland-II produces standard scores in four domains: Communication, Daily Living Skills, Socialization, and Motor Skills.
• Wechsler Abbreviated Scale of Intelligence (WASI)
  The WASI produces indices for the overall level of intellectual functioning (FSIQ), as well as Verbal and Performance. Subtests include Vocabulary, Similarities, Block Design, and Matrix Reasoning
• Wechsler Intelligence Scale for Children—Fourth Edition (WISC-IV)
  The WISC-IV produces indices (scales) for the overall level of intellectual functioning (FSIQ), as well as Verbal, Perceptual Reasoning, Processing Speed, and Working Memory. The 15 subtests include Vocabulary, Comprehension, Information, Similarities, Word Reasoning, Picture Concepts, Picture Completion, Digit Span, Letter-Number Sequencing, Cancellation, Arithmetic, Block Design, Coding, Symbol Search, and Matrix Reasoning
• Mullen Scales of Early Learning

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