Hayley C Leonard, Rachael Bedford, Tony Charman, Mayada Elsabbagh, Mark H Johnson, Elisabeth L Hill, Simon Baron-Cohen, Patrick Bolton, Susie Chandler, Holly Garwood, Karla Holmboe, Kristelle Hudry

Recently, evidence of poor or atypical motor skills in autism spectrum disorder has led some to argue that motor impairment is a core feature of the condition. The current study uses a longitudinal prospective design to assess the development of motor skills of 20 children at increased risk of developing autism spectrum disorder, who were recruited and tested at 9 and 40 months of age, on the basis of having an older sibling diagnosed with the condition. All children completed a range of motor, face processing, IQ and diagnostic assessments at a follow-up visit (aged 5-7 years), providing a detailed profile of development in this group from a number of standardised, parental report and experimental measures. A higher proportion of children than expected demonstrated motor difficulties at the follow-up visit and those highlighted by parental report as having poor motor skills as infants and toddlers were also more likely to have lower face processing scores and elevated autism-related social symptoms at 5-7 years, despite having similar IQ levels. These data lend support to the argument that early motor difficulties may be a risk factor for later motor impairment as well as differences in social communication and cognition, traits that are related to autism spectrum disorder.