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.