Assessment of action-level Imitation, using the Preschool Imitation and Praxis Scale, contribute to early diagnosis of autism spectrum disorders

Abstract

BACKGROUND Researchers consistently reported imitation impairments in children with ASD. Our basic assumption is that in young children with ASD action-level imitation or the pure perception-action coupling is delayed. Differential diagnostic aspects of action-level imitation have not yet been studied. OBJECTIVES To explore imitation in young children suspected of ASD, using a multidimensional action-level imitation test. METHODS Preschoolers [N=71, CA 23 till 54 m, IQ above 70] suspected of ASD and referred to University Autism Clinics were divided in two groups according to their ADOS-G classification: 48 children with ASD [19 with autistic disorder (AD) and 29 with PDD-NOS] and 23 children without ASD. Children were age-matched and assessed on action-level imitation and four other developmental domains: gross and fine motor function, cognition and receptive language. Action-level imitation was judged using the Preschool Imitation and Praxis Scale (PIPS), a newly developed instrument to measure meaningful and non-meaningful procedural, single and sequential bodily imitation. Age norms were derived from PIPS scores of 498 typically developing children. RESULTS Within-group analyses revealed that both groups performed less well than expected for their chronological age on all developmental domains, with the exception of cognition in children with ASD and receptive language in children without ASD. Between-group analyses revealed that children with ASD performed significantly poorer compared to children without ASD on imitation, gross motor function and receptive language. Sub analysis revealed that children with PDD-NOS and AD did not differ from each other on all developmental domains, with the exception of sequential bodily imitation. CONCLUSION This study is the first to investigate action-level imitation in young children suspected of ASD with a standardised multidimensional imitation test: the Preschool Imitation and Praxis Scale (PIPS). Findings of this study indicate that the investigation of action-level imitation can contribute to the diagnosis of ASD.