The Effect of Combined Intervention on Improvement of Early Lexical Development in Minimally Verbal Children with Autism Spectrum Disorder.

Background: Autism spectrum disorder (ASD) is a neurodevelopmental disorder defined by severe communication deficits and limited and repetitive behavioral tendencies. There are several treatment approaches and methods for minimally verbal children with ASD; nonetheless, there is inconclusive evidence about how early lexical development could be improved. The present study aimed to investigate the effect of combined intervention derived from the principles of different theories-including contemporary behaviorism, schemas, sociocultural, and event representation theories-to improve early lexical development in minimally verbal children with ASD.

Methods: In this single-group pretest-posttest study, 10 children with ASD (mean age, 47.9 ± 8.3 months), including 7 boys and 3 girls, participated. Participants received 16 intervention sessions in 8 weeks. The combined intervention consisted of various methods derived from contemporary behaviorism, schemas, sociocultural, and event representation approaches. The MacArthur-Bates Communicative Development Inventory 1 (Infant form) assessed early lexical development before and after intervention and after a 2-month follow-up. The Friedman test was used to analyze the data, and pairwise comparisons were performed with the Will-Coxon test. Cohen's d was used to investigate the effect sizes.

Results: Significant increases in expressive vocabulary (P < 0.001) and receptive language (P < 0.001) were seen after the end of the intervention and at the follow-up (P = 0.005). Large effect sizes were found for expressive vocabulary (d = 3.7) and receptive vocabulary (d = 2.17).

Conclusion: This study suggests that the combination of intervention based contemporary behaviorism, schemas, sociocultural, and event representation approaches improved receptive and expressive vocabulary in minimally verbal children with ASD.