The interaction of fine motor, gesture, and structural language skills: The case of autism spectrum disorder.

Motor skill differences have been consistently reported in individuals with ASD. Associations between motor skill and social communication skills have been reported in both typical development (TD) and autism spectrum disorder (ASD). The current study extends these findings to characterize performance on a fine motor imitation task, probing skills as a predictor of social and communicative functioning, and co-speech gesture use. These research questions were addressed by a secondary analysis of data collected during a previous study characterizing a cohort of individuals who were diagnosed with ASD in early childhood but lost the autism diagnosis (LAD) by the time of adolescence. Fine motor imitation skills were compared between 14 individuals with LAD, 15 individuals with autism spectrum disorder (ASD), and 12 typically developing (TD) individuals. LAD and TD groups had more advanced fine motor imitation skills than the ASD group, and abilities were significantly associated with ASD symptoms and amount of gesture use (though there was a counterintuitive interaction between group and fine motor skill in the LAD and TD groups only, in which lower motor skills predicted more ASD symptoms; this relationship was of a small effect size and is likely driven by the compressed range of fine motor skills in these two groups). Findings suggest that fine motor skills normalize along with social communication skills and restricted and repetitive behaviors and interests in individuals who lose the ASD diagnosis, and that individuals with better fine motor abilities produce more co-speech gesture.