Assessment of cognition and language in the early diagnosis of autism spectrum disorder: usefulness of the Bayley Scales of infant and toddler development, third edition

BACKGROUND: The aim of this study was to test the usefulness of the Cognitive and Language scales Bayley‐III in the early assessment of cognitive and language functions in the context of an autism spectrum disorder (ASD) diagnosis. This paper focuses on the application of the Bayley‐III and studies the predictive value of the test result in children with ASD with different levels of verbal ability. METHOD: A sample of 135 children (121 boys, 14 girls) with a confirmed ASD diagnosis at age 4 years were assessed with the Bayley‐III before 42 months of age (m = 36.49, s = 4.46) and later with other rating scales of different psychological and psycholinguistic functions as part of a longitudinal study [McCarthy Scales of Children's Abilities (MSCA) (n = 48, 90% boys), Kaufman Assessment Battery for Children (K‐ABC) (n = 38, 87% boys) or Illinois Test of Psycholinguistic Abilities (ITPA) (n = 44, 89% boys)]. Age assessment in months: MSCA (m = 48.80, s = 3.33), K‐ABC (m = 51.80, s = 7.17) and ITPA (m = 54.48, s = 3.34). RESULTS: Lower scores on the cognitive and language Bayley‐III scales before 3.5 years of age predicted lower cognitive and oral language levels at 4 years of age. A significant correlation was found between the Cognitive Bayley‐III Scale and the General Cognitive MSCA Scale, and with the Compound K‐ABC Mental Processing. An association between the nonverbal cognitive level and oral language level acquired at 4 years of age was found. CONCLUSIONS: The Bayley‐III is a useful instrument in cognitive and language assessment of ASD.