Objective: Literature shows that cognitive function of a child with autism spectrum disorder (ASD) is positively associated with later outcomes. However, developmental and cognitive assessments have not been consistently completed at the time of diagnosis in many clinical settings. It is uncertain whether a standardized parent adaptive questionnaire will help predict later cognitive functioning. This study explored the utility of a standardized questionnaire in predicting future cognitive functioning in children with ASD.
Method: Children aged 24 to 59 months consecutively diagnosed with ASD from January 2011 to October 2013, and had a cognitive assessment completed at a later time point, were included in the study (N=113). Descriptive data on demographic characteristics, Autism Diagnostic Observation Schedule (ADOS) scores, Vineland Adaptive Behavior Scales-II (VABS-II) standard scores at the time of ASD diagnosis and later cognitive scores of the cohort were presented. VABS-II standard scores at the time of diagnosis were used to predict best estimate nonverbal cognitive scores using linear regression models, after controlling for gender, race, age at diagnosis, and ADOS scores.
Results: In this cohort, 88.5% were boys and the mean age of diagnosis was 48.4 months. The adaptive behaviour profile of the study population showed motor skills>communication>daily living>socialization skills, consistent with previous studies on verbal children with ASD. The VABS-II adaptive behaviour composite score and all the VABS-II domain scores at the time of diagnosis significantly predict later cognitive functioning. The adaptive behaviour composite score best predicts later nonverbal cognitive standard scores (p<0.001, R2=0.446). The age at diagnosis and ADOS social score were also predictors of later nonverbal IQ scores.
Conclusion: In clinical settings where cognitive assessments cannot be completed at the time of diagnosis, there may be utility in using the VABS-II to better understand the cognitive functioning of children with ASD.