Adaptive Behavior in Young Children with High and Low Functional Autism Spectrum Disorders

Background: Adaptive behavior in autism is highly variable (Burack & Volkmar, 1992). Researchers found that overall or sub-domain adaptive functioning was lower in children with autistic spectrum disorders (ASDs) compared to their same cognitive function controls. This adaptive functioning pattern that was different from those children with other diagnoses was called ‘autism profile’, could be observed when these children were very young (Stone et al., 1999). Furthermore, the profiles within domains of adaptive behavior skills might be different between higher and lower cognitive function individuals with ASDs. However, this finding has not consistently been reported.

Objectives: This study was to examine the development in adaptive behavior skills in young children with ASDs in Taiwan, comparing to children with developmental delay (DD) and typical development (TD). Furthermore, we explored variability in adaptive behavior within children with ASDs (high functional autistic spectrum disorders (HFASD) vs. low functional autistic spectrum disorders (LFASD)). Well-established and wide-used test, Vineland Adaptive Behavior Scales-Second Edition (VABS-II), was used to assess the adaptive behavior skills.

Methods: Participants included 116 individuals, 51 children with ASDs (41 autistic disorder and 10 children with Pervasive Developmental Disorder – Not Otherwise Specified, age 2:4 to 5:1), 32 children with DD (age 3:6 to 5:0) matched on mental age (MA) and CA, and 33 children with TD (age 2:3 to 2:9) matched on MA, who were recruited to the study. Autism diagnosis was confirmed with the ADOS (Autism Diagnostic Observation Schedule) and clinical impression (DSM-IV-TR). Verbal mental age obtained from the Mullen Scales of Early Learning. VABS-II was assessed by interview with caregiver(s).

Results: Two-way mixed ANOVA was conducted to compare scores on adaptive behavior domains (Communication, Daily Living Skills, Socialization, and Motor Skills) between groups (ASDs, DD, and TD). There was a significant main effect for groups but not adaptive behavior domains. TD group had better adaptive functioning than ASDs or DD. The interaction effect reached statistical significance indicated that there was a different adaptive functioning profile between groups. Follow up ANOVAs showed that in three domains, communication, daily living skills, and motor skills, TD had higher VABS-II scores than ASDs and DD, but the latter two group did not show the difference. In addition, comparing to DD and TD, children with ASDs was significantly poorer function in socialization domain. The differences in VABS-II scores between children with high and low functional ASDs were also analyzed. There was a significant main effect for groups. HFASD group had better adaptive functioning than LFASD group. The main effect for domain and the interaction effect did not reach statistical significance.

Conclusions: Relative to children with TD, both young children with ASDs and DD had weaker adaptive behavior skills. But in socialization domain, children with ASDs were much poorer than children with DD, even though their MA and CA were the same. HFASD had better adaptive behavior skills than LFASD, but their profile of adaptive behavior skills was similar. In summary, children with ASDs, regardless of their cognitive function, showed similar weakness in adaptive functioning.