Objectives: To examine the rates of change (RoC) during and following EIBI, using multi-wave measures of expressive and receptive language and adaptive behavior obtained over 4-5 years.
Methods: Data were collected for 53 children with ASD prior to the initiation of EIBI (T1) and 6, 12, 24, 32, and 53 months later, using the Peabody Picture Vocabulary Test (PPVT), Expressive One-Word Picture Vocabulary Test, Preschool Language Scale, and Vineland Adaptive Behavior Scale (VABS). SAS proc mixed analyses were used to examine the developmental trajectories for each outcome measure during and post EIBI. Chronological age (CA) was used as a measure of time and nonverbal IQ (NVIQ) and autism severity scores at T1 were examined as predictors of the intercepts and slopes. Developmental trajectories were also estimated for typical children, using information from relevant test manuals.
Results: On all measures except the VABS communication and socialization subscales, RoCs for the autism sample approached or exceeded those of typically developing children of the same CA during 2 years of EIBI. On the two VABS subscales, this was also true for children with NVIQ scores ≥50. Following EIBI termination, RoCs for all measures except PPVT decreased to 25%-50% of the EIBI rates.
Conclusions: This sample of children receiving eclectic EIBI demonstrated greatly accelerated language and adaptive skill development over 2 years. However, these gains were not maintained at the same rate after EIBI was discontinued at school entry. This suggests that terminating EIBI at age 6 may not maximize children's developmental potential.