Nature of motor impairments in autism spectrum disorder: A comparison with developmental coordination disorder

Introduction: Several authors have suggested the existence of motor disorders associated with developmental coordination disorder (DCD) in individuals with autism spectrum disorder (ASD). However, there are few comparative studies of psychomotor profiles that include assessments of neurological soft signs in children with ASD or DCD. We used a neuropsychomotor assessment for children with ASD from a standardized neurodevelopmental examination to understand the nature of the difficulties these children encounter. To uncover the differences and similarities in psychomotor profiles, we compared the profiles of children with ASD with those of children with DCD and focused on two recently described DCD subgroups: visuospatial-constructional (VSC) and mixed (MX).Methods: We compared 18 children with ASD and 58 children with DCD (33 with VSC-DCD and 25 with MX-DCD) who were assessed with a battery of French-language tests (the NP-MOT) to evaluate the neuropsychomotor functions associated with visual perception and visual-spatial-motor structuring.Results: Although there were similarities between the profiles of children with ASD and those with DCD (VSC-DCD or MX-DCD), these similarities were not associated with the predictive diagnostic markers that characterized subtypes of DCD. Instead, many variables (visuospatial-motor structuration, synkinetic movements, dynamic balance, manual dexterity, coordination, praxis, bodily spatial integration, and digital perception) differed among the three groups; the best performance was observed in the children with ASD.Conclusion: The neuropsychomotor profiles of children with ASD and those with VSC-DCD or MX-DCD differed, and these differences are discussed. Our results highlight that impairments of ASD are specific about lateralization disturbances and support the hypothesis of proprioceptive impairment due to visual fixation problems influenced by muscular tone in relation to the subcortical and cortical structures and possible interhemispheric disorder. Thus, some neuropsychomotor functions that underpin both gestures and a set of motor skills are affected.