Abstract
Authors contrasted Bracken Basic Concept Scale: Receptive, Third Edition (BBCS: R-3) test performance between 57 children with intellectual disability (ID) and 76 children with autism spectrum disorder (ASD) and ID. BBCS: R-3 School Readiness Composite (SRC) and Self-/Social Awareness subtests were analyzed. Multivariate analysis of covariance revealed no differences between groups on SRC performance; however, children with ID demonstrated better mastery of self-/social awareness concepts when compared to children with ASD. Within the group of children with ASD, mastery of school-based concepts exceeded mastery of self-/social awareness concepts. Findings suggest relatively greater delays in mastery of self-/social awareness concepts for young children with ASDs when compared to mastery of other concepts.
Efforts to improve early identification of Autism Spectrum Disorders (ASD) have highlighted the challenges in diagnosing ASD in children with other coexisting conditions. The diagnosis of ASD in children with intellectual disability (ID), for example, can be quite complex. Individuals with ASD display difficulties in the areas of communication, social interaction, and stereotyped and repetitive interests and behaviors (DSM-IV-TR [Diagnostic and Statistical Manual of Mental Disorders-IV-Text Revision]; American Psychiatric Association [APA], 2000). Due to the global nature of the problems that arise within the context of an ID, many individuals with ID display similar deficits (Bielecki & Swender, 2004). Despite the overlap in symptoms, there is evidence to suggest that deficits in social functioning are more severe in children with ASD than in children with ID without ASD (Carpentieri & Morgan, 1996; Klin, Volkmar, & Sparrow, 1992; Lockyer & Rutter, 1970; Lord & Schopler, 1989; Molloy et al., 2009; Rodrigue, Morgan, & Geffken, 1991). The domains of socialization and communication have typically been the most impaired aspects of adaptive functioning (de Bildt et al., 2005; Stone, Ousley, Hepburn, Hogan, & Brown, 1999; Vig & Jedrysek, 1995). Differentiating between deficits due to ID alone, versus deficits due to ASD in conjunction with ID can be one of the most difficult components of an assessment for ASD. Therefore, identification of new methods that will assist with differential diagnosis of these disorders is important, and evaluating assessment tools that measure understanding of social concepts offers one an avenue to accomplish this goal.
Although difficulties with social awareness and social interaction may be common to both ID and ASD, social deficits are a core symptom of ASD (Constantino, Przybeck, Friesen, & Todd, 2000) which suggests that a comprehensive assessment of these skills may assist in the differential diagnosis and prescriptive interventions for these complex cases. Researchers using semistructured interviews and behavior observations, including the Autism Diagnostic Interview-Revised (ADI-R; Rutter, LeCouteur, & Lord, 2003) and the Autism Diagnostic Observation Schedule (ADOS; Lord, Rutter, DiLavore, & Risi, 1999), have demonstrated the utility of assessing social behavior when differentiating children with ID and ASD/ID (Hartley & Sikora, 2010; Matson, Dempsey, LoVullo, & Wilkins, 2008). However, research has indicated that even the ADOS and ADI-R tend to overclassify individuals with profound ID as having ASD, highlighting the difficulty of differentiating these disorders and the importance of using multimodal assessment for diagnosis (Risi et al., 2006). Further research is needed to explore and clarify the differences in social functioning in individuals with ASD and/or ID and to determine how these differences can assist in diagnosis and treatment planning.
A first step toward achieving this goal may be to subdivide the broad domain of social functioning into smaller, more defined skill subsets. While it is clear that there is significant variability in the social skills of individuals diagnosed with ASD (Ozonoff, Goodlin-Jones, & Solomon, 2005), it may be possible to obtain a general profile of strengths and weaknesses typically seen in individuals with ASD and/or ID. For example, Theory of Mind research has demonstrated that when compared to typically developing peers, individuals with ASD often have more difficulty understanding others’ feelings, thoughts, and beliefs (Baron-Cohen, Leslie, & Frith, 1985; Colle, Baron-Cohen, & Hill, 2007; Leslie & Frith 1988). Individuals with ID, on the other hand, have been shown to have generally the same level of skill on Theory of Mind tasks as typically developing individuals matched on developmental age; although some variability in Theory of Mind skills has been noted depending on how the skills are assessed (Baron-Cohen et al., 1985; Thirion-Marissiaux & Nader-Grosbois, 2008). Research has also shown that individuals with ASD, especially young children, are more likely to have difficulty recognizing others’ emotions than typically developing peers (Kuusikko et al., 2009; Rump, Giovannelli, Minshew, & Strauss, 2009). Finally, children with ASD have also demonstrated deficits in social orienting, joint attention, and attention to distress when compared to typically developing peers and peers with developmental delays (Dawson et al., 2004; Dawson, Meltzoff, Osterling, Rinaldi, & Brown, 1998). These few examples demonstrate the utility of examining social behaviors in a variety of contexts in order to develop a better understanding of the unique needs of individuals with ASD and subsequently create more effective assessment tools and intervention techniques (for more detailed review see: Matson & Wilkins, 2007; White, Keonig, & Scahill, 2007).
Method
Participants
Data were collected at a university-based clinic serving children with developmental disabilities and their families in the American Southeastern region. Participants were 133 children, 57 children diagnosed with ID (ID group), and 76 diagnosed with ID and ASD (ASD/ID group). Mean chronological age was 55.85 (SD = 14.95) months, with the ID group roughly 6 months older than the ASD/ID group, t(94.91) = 2.19, p = .03. Mean IQ for the entire sample was 51.10 (SD = 14.95) with the ID group earning IQs roughly 5 points higher than the ASD/ID group, t(131) = 2.20, p = .03. The majority of participants were males (78.36%); proportions of males and females were equal across groups, [χ2(1, N = 133) = 1.19, ns]. The majority of caregivers self-reported race as African American (56.39%); 36.39% of caregivers self-reported race as Caucasian. Race characteristics did not differ across groups, [χ2(4, N = 133) = 2.32, ns]. Table 1 provides additional demographic information.
Participants’ Demographic Information (N = 133).
Note. ID = Intellectual Disability; ASD/ID = Autism Spectrum Disorder and Intellectual Disability; CARS-2 = Childhood Autism Rating Scale, Second Edition; Vineland-2 ABC = Vineland Adaptive Behavior Scales, Second Edition, Survey Form; Adaptive Behavior Composite; SIB-R EDF = Scales of Independent Behavior-Revised Early Development Form Composite.
Measures
Stanford-Binet Intelligence Scales, Fifth Edition (SB5; Roid, 2003)
The SB5 is a measure of children’s general cognitive functioning and was used to evaluate the presence of cognitive delays necessary for diagnosis of ID. The SB5 yields an Full Scale IQ (FSIQ) standard score with a mean of 100 and a standard deviation of 15 and demonstrates strong psychometric evidence to support its use.
Childhood Autism Rating Scale, Second Edition (CARS-2; Schopler, Van Bourgondien, Wellman, & Love, 2010)
Identical to its predecessor in content, the CARS-2 Standard Version is a 15-item rating scale designed to assess the presence of symptoms associated with ASD. The CARS-2 Standard Version was completed by the evaluation team and used to assist in diagnostic decision making regarding the presence or absence of an ASD. The CARS-2 Standard Version was designed for children below 6 years of age who demonstrate communicative and cognitive delays or impairments (e.g., overall IQ of 79 or lower; Schopler et al., 2010). The CARS-2 Standard Version was normed on 1,034 individuals diagnosed with autism. Internal consistency reliability for the CARS-2 Standard Version is .93, as measured by coefficient α; corrected item-total correlations for the 15 items range from .43 to .81. Temporal stability for the CARS-2 total score is .88 (1-year test–retest interval); and interrater reliability for the total score is .84, 280 pairs of raters (Schopler et al., 2010). Evidence for concurrent validity is presented in the CARS-2 manual as evidenced by a r = .79 correlation between CARS-2 Standard Version scores and Autism Diagnostic Observation Scale total raw scores for 37 individuals.
Adaptive functioning: Vineland Adaptive Behavior Scales, Second Edition: Survey Form (Vineland-2; Sparrow, Cicchetti, & Balla, 2005) and Scales of Independent Behavior-Revised (SIB-R; Bruininks, Woodcock, Weatherman, & Hill, 1996)
Adaptive functioning for each participant was measured by one of the following measures: (a) Vineland-2, Adaptive Behavior Scales Composite (n = 66; Sparrow et al., 2005); or (b) SIB-R, Early Development Form (SIB-R: ED; n = 67). Both measures yield a standard score for composites with a mean of 100 and a standard deviation of 15. To assess adaptive communication, all caregivers completed the Communication Domain of the Vineland-2, regardless of whether the Vineland-2 or SIB-R: ED was completed for the purpose of documenting overall adaptive functioning. The Vineland-2 Communication scale yields a domain score with mean of 100 and standard deviation of 15.
Bracken Basic Concept Scale—Third Edition: Receptive (Bracken, 2006)
The BBCS-3: R is a receptive measure of basic concepts that was normed on 640 children ages 3 years 0 months to 6 years 11 months (Bracken, 2006). This study examined the receptive understanding of basic concepts using two scales. The Bracken-3 School Readiness Composite (SRC) measures receptive language for the following concepts: colors, letters, numbers/counting, sizes/comparisons, and shapes. The Self/Social-Awareness (SSA) subtest of the BBCS-3: R measures receptive language for: affective feelings, gender, familial relationships, health, and physical states. Performance was measured using a scaled score (M = 10, SD = 3). The internal consistency coefficients for the SRC r = .95 and SSA r = .91 are excellent.
Procedure
Data were obtained from a record review of results of psychological assessments of clinic patients. The study was approved by the Institutional Review Board at the University of Tennessee Health Science Center and informed caregiver consent for use of assessment data was obtained prior to the assessment. Diagnoses were based on a comprehensive assessment completed under the supervision of a licensed psychologist specializing in assessment of young children with ASD, ID, and other developmental disorders. Diagnostic consensus was achieved via a team evaluation at University of Tennessee Health Science Center. Eighty-seven percent of the participants were evaluated by a multidisciplinary team, and the remaining participants were evaluated by a psychology team. Participants were assigned to either the ID or ASD/ID groups based on a review of records. Cognitive and adaptive functioning were examined, as well as ASD diagnosis status. Criteria for inclusion in the ID group were an FSIQ score of less than 70, and an Adaptive Composite score of less than 75. Each individual in this group also had a clinical diagnosis of Mild or Moderate Intellectual Disability (DSM-IV-TR; APA, 2000) or Mixed Development Disorder (ICD-9-CM [International Classification of Diseases, 9th Revision, Clinical Modification]; MediCode, 1998). The same criteria for FSIQ and adaptive functioning were used for the ASD/ID group; however, each individual in this group also had a clinical diagnosis of Autistic Disorder or Pervasive Developmental Disorder, Not Otherwise Specified (DSM-IV-TR; APA, 2000). Bracken SRC and SSA scores were not used to determine diagnosis.
Results
Vineland-2 and SIB-R: ED administrations were represented equally across groups, [χ2(1, N = 133) = 1.69, ns]. Neither Vineland-2 Adaptive Behavior Scale: Survey Form Composite, t(64) = 0.45, ns, nor SIB-R: ED scores differed across groups t(65) = 1.78, ns (see Table 1). CARS-2 scores were available for 118 participants, 45 with ID and 73 with ASD/ID; CARS-2 total scores differed across groups, t(116) = 13.80, p < .001, with the ASD/ID group earning significantly higher CARS-2 total scores (see Table 1).
A multivariate analysis of covariance (MANCOVA) was utilized to evaluate the effect of diagnosis on school readiness and self-/social-awareness while accounting for the potential confounding effects of age, IQ, and communication. Group was identified as the independent variable (i.e., ID or ASD/ID), BBCS: 3-R raw and subscale scores were entered as dependent variables, and age, SB5 IQ scores, and Vineland-2 Communication scores were entered as covariates (see Table 2 for descriptive statistics). Age was identified as a covariate due to differences between groups; IQ and adaptive communication scores were identified as covariates due to their theoretical relationships with receptive vocabulary skills and the observation that IQs differed across diagnostic groups.
Dependent Variables and Covariates Within the Multivariate Analysis of Covariance (N = 133).
Note. ID = Intellectual Disability; ASD/ID = Autism Spectrum Disorder and Intellectual Disability; BBSC-3: SRC = Bracken Basic Concept Scale, Third Edition, Receptive: School Readiness Composite; BBSC-3: SSA = Bracken Basic Concept Scale, Third Edition, Receptive: Social and Self Awareness Subscale; Vineland-2 Communication = Vineland Adaptive Behavior Scales, Second Edition, Survey Form, Communication Domain.
The MANCOVA yielded a significant overall effect for group, Wilks’ Λ = .79, F(4, 125) = 8.51, p < .001, η2 = .21. Follow-up univariate tests revealed no group differences for BBSC-3 SRC scaled scores, F(1, 133) = 1.59, ns, or BBCS-3 SRC raw scores, F(1, 133) = 2.55, ns. BBCS-3 SSA scaled scores, F(1, 133) = 15.78, p < .001, η2 = .11, and BBCS-3 SSA raw scores, F(1, 133) = 9.99, p < .01, η2 = .07, differed across groups. Children with ID earned significantly higher self-social awareness scaled and raw scores when compared to their counterparts diagnosed with ASD/ID (see Table 2 for means and standard deviations).
Additional Analysis Excluding Participants With BBCS-3 Raw Scores of Zero
Review of BBCS-3 performance revealed that 36 participants (27% of the sample) earned SRC raw scores of zero, and 60 participants (45% of the sample) earned SSA raw scores of zero. Participants with ASD/ID were overrepresented in the subgroup of participants earning SRC raw scores of zero, [χ2(1, N = 133) = 11.05, p < .01; Φ = .29, p < .01], and those earning SSA raw scores of zero, [χ2(1, N = 133) = 14.23, p < .001; Φ = .33, p < .01]. Authors conducted an additional MANCOVA with participants who earned SRC and SSA raw scores greater than zero; the subsample consisted of 70 participants, 41 with ID and 29 with ASD/ID. Dependent variables, independent variables, and covariates were identical to the previous MANCOVA analysis. The additional MANCOVA yielded a significant overall effect for group, Wilks’ Λ = .70, F(4, 62) = 6.79, p < .001, η2 = .30. Follow-up univariate tests revealed significant group differences for all BBSC-3 scores. For BBCS-3 SRC scaled scores, children with ASD/ID (M = 5.14) significantly outperformed children with ID (M = 3.12), F(1, 65) = 12.29, p < .01, η2 = .16. In contrast, children with ID earned significantly higher SSA scaled scores (M = 3.41) when compared to their counterparts diagnosed with ASD/ID (M = 2.56), F(1, 65) = 4.54, p < .05, η2 = .07.
Within-group comparisons using paired sample t tests were conducted to determine if BBSC-3 subtest performance differed within each group. Children with ASD/ID (n = 29) performed significantly higher on the SRC when compared to the SSA, t(28) = 4.72, p < .001. In contrast, children with ID (n = 41) performed similarly across both BBCS-3 scaled scores, t(40) = 1.36, ns.
Discussion
Research has highlighted the need for early, accurate diagnosis of ASD (Filipek et al., 1999; Ozonoff et al., 2005), with assessment of social functioning being an essential component of this assessment, especially in children who have comorbid ID (Hartley & Sikora, 2010). Researchers have systematically studied components of typical social development in an effort to gather knowledge on the specific strengths and weaknesses that characterize individuals with an ASD (Matson & Wilkins, 2007; White et al., 2007). The purpose of the current study was to extend the literature in this area by conducting a preliminary analysis of the receptive understanding of basic school readiness and self-/social-awareness concepts in children with ID and ASD/ID. The results of this study contribute to the growing research base that identifies specific strengths and deficits in individuals with ASD/ID or ID, and it is hoped that these findings will lead to improvements in clinical assessment and intervention.
Results indicated that receptive understanding of self-/social-awareness concepts was significantly lower for the ASD/ID group as compared to the ID group when age, IQ, and communication skills were controlled. Differences between the two groups were also apparent when participants with raw scores of zero were removed to control for floor effects. This analysis showed that the ASD/ID group had significantly higher school readiness scores than the ID group. These results suggest that basic concepts such as color, letter, and letter recognition are relative strengths for children with ASD/ID.
Further, these results reveal a unique profile for each diagnostic group. The ID group displayed similar performance on both scales, suggesting that receptive understanding was equally developed across the areas measured. In contrast, the ASD/ID group’s performance on the School Readiness Composite exceeded one standard deviation above their performance on the Self/Social-Awareness subtest, indicating a significant weakness in receptive understanding of concepts related to social interaction, as opposed to more basic academic concepts (e.g., colors, numbers). Detection of a specific area of weakness such as receptive understanding of social concepts could be a critical tool in conceptualization of a complex clinical presentation and the development of targeted intervention programs.
This preliminary study was limited by small group sizes, especially when participants with raw scores of zero were removed; however, it highlights a need for future research regarding the unique neurocognitive profiles of individuals with ASD/ID or ID. The participants in the study were selected from a clinical sample, therefore, strict inclusion criteria for language ability and comorbid diagnoses were not utilized, which likely resulted in increased variability within and between groups. If future studies utilize more consistent and stringent inclusion criteria and consistent and stringent instrument selection for the diagnosis of ASD, more distinct differences between groups may be found. As these assessment profiles are further delineated, it will be important to determine whether the deficits noted on standardized assessment measures are also observed in the child’s natural environment. Future work in this area will provide evidence of the utility of this approach to assessment and intervention development.
Footnotes
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research was partially funded by Maternal and Child Health Bureau—USPHS Grant 6T73MC00038-10 and Administration on Developmental Disabilities—Grant 90-DD-00578.