Clinical Psychological Science 1–7 © The Author(s) 2015 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/2167702615576697 cpx.sagepub.com Brief Empirical Report Autism spectrum disorders (ASD) are a group of hetero- geneous and common neurodevelopmental disorders (prevalence of around 1%; Centers for Disease Control and Prevention, 2014) characterized by early emerging impairments in social interaction and communication, as well as restrictive and repetitive behaviors (American Psychiatric Association [APA], 2013). Previous work has shown that children who go on to receive an ASD diag- nosis express impairments in a range of abilities already during the first year of life, including problems with attention, unusual temperament characteristics, and diminished social motivation (Jones, Gliga, Bedford, Charman, & Johnson, 2014). The risk for ASD in infant siblings of children with ASD is more than tenfold com- pared to the risk in the general population (Constantino, Zhang, Frazier, Abbacchi, & Law, 2010; Sandin et al., 2014). The high familial risk makes longitudinal studies of infant siblings a feasible strategy in the search for early ASD markers (for a review, see Jones et al., 2014). Motor impairments are not part of the diagnostic crite- ria of ASD (APA, 2013) and are typically not considered a core feature of the disorder. However, it is well estab- lished that motor problems are common within this pop- ulation (e.g., Jansiewicz et al., 2006; Lai, Lombardo, & Baron-Cohen, 2014; Minshew, Sung, Jones, & Furman, 2004). In particular, studies on adults have shown that individuals with ASD often display longer reaction times before starting a reaching movement than typically devel- oping (TD) controls (Glazebrook, Elliott, & Szatmari, 2008). Other motor deficits in ASD include atypical basic movement kinematics (Cook, Blakemore, & Press, 2013) and longer movement times (Stoit, van Schie, Slaats- Willemse, & Buitelaar, 2013). 576697 Corresponding Author: Therese L. Ekberg, Department of Psychology, Uppsala University, Box 1225, 751 42 Uppsala, Sweden E-mail: therese.ekberg@psyk.uu.se Reduced Prospective Motor Control in 10-Month-Olds at Risk for Autism Spectrum Disorder Therese L. Ekberg 1 , Terje Falck-Ytter 1,2 , Sven Bölte 2,3 , Gustaf Gredebäck 1 , and the EASE Team 1 Uppsala Child & Babylab, Department of Psychology, Uppsala University; 2 Center of Neurodevelopmental Disorders at Karolinska Institutet (KIND), Pediatric Neuropsychiatry Unit, Department of Women’s & Children’s Health, Karolinska Institutet; and 3 Division of Child and Adolescent Psychiatry, Stockholm County Council Abstract Motor impairments are not a part of the diagnostic criteria for autism spectrum disorder (ASD) but are overrepresented in the ASD population. Deficits in prospective motor control have been demonstrated in adults and older children with ASD but have never before been examined in infants at familial risk for the disorder. We assessed the ability to prospectively control reach-to-grasp actions in 10-month-old siblings of children with ASD (high-risk group, n = 29, 13 female) as well as in a low-risk control group (n = 16, 8 female). The task was to catch a ball rolling on a curvilinear path off an inclined surface. The low-risk group performed predictive reaches when catching the ball, whereas the high-risk group started their movements reactively. The high-risk group started their reaches significantly later than the low-risk group (p = .03). These results indicate impaired prospective motor control in infants susceptible for ASD. Keywords prospective motor control, autism spectrum disorder, siblings, motor development Received 12/4/14; Revision accepted 2/12/15