ABBREVIATION DCD Developmental coordination disorderAIM Developmental coordination disorder (DCD) is a significant disorder of childhood, characterized by core difficulties in learning fine and ⁄ or gross motor skills, and the attendant psychosocial problems. The aim of the meta-analysis presented here (the first on DCD since 1998) was to summarize trends in the literature over the past 14 years and to identify and describe the main motor control and cognitive deficits that best discriminate children with DCD from those without.

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For children with Developmental Coordination Disorder (DCD), the real-time coupling between frontal executive function and online motor control has not been explored despite reported deficits in each domain. The aim of the present study was to investigate how children with DCD enlist online control under task constraints that compel the need for inhibitory control. A total of 129 school children were sampled from mainstream primary schools. Forty two children who met research criteria for DCD were compared with 87 typically developing controls on a modified double-jump reaching task. Children within each skill group were divided into three age bands: younger (6-7 years), mid-aged (8-9), and older (10-12). Online control was compared between groups as a function of trial type (non-jump, jump, anti-jump). Overall, results showed that while movement times were similar between skill groups under simple task constraints (non-jump), on perturbation (or jump) trials the DCD group were significantly slower than controls and corrected trajectories later. Critically, the DCD group was further disadvantaged by anti-jump trials where inhibitory control was required; however, this effect reduced with age. While coupling online control and executive systems is not well developed in younger and mid-aged children, there is evidence of ageappropriate coupling in older children. Longitudinal data is needed to clarify this intriguing finding. The theoretical and applied implications of these results are discussed.3

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ABBREVIATIONS DCD Developmental coordination disorder GMLT Groton Maze Learning Test MAND McCarron Assessment of Neuromuscular Development NDI Neurodevelopmental Index TMD Typical motor development AIM To analyse the development of motor skill and executive function in school-aged children with and without developmental coordination disorder (DCD). METHOD Using a longitudinal design, 186 children (86 males, 100 females) aged 6 to 11 years at Time 1 were tested over a 2-year period, 52 of whom were diagnosed with DCD at Time 1 (27 males, 25 females; mean age 8y 5mo, SD 1y 6mo) using DSM-5 criteria. The McCarron Assessment of Neuromuscular Development assessed motor status at Time 1 and at 2-year follow-up (Time 2). Executive function was assessed using a well-validated measure, the Groton Maze Learning Test. RESULTS The DCD cohort at Time 1 had moderate incidence of executive function deficit (41%). Most importantly, at a group level, children with persisting DCD (across Times 1 and 2) also showed significantly lower levels of executive function than children with typical motor development at both time points. At an individual level, around 26% of children in this group had persisting executive function deficits relative to normal ranges of performance. INTERPRETATION Children with persisting DCD are at significant risk of executive function issues. The combination of motor and cognitive issues as a potential risk factor in the longerterm development of children is discussed.