Persistence of motor-cognitive inhibition deficits in children with developmental coordination disorder (DCD): a longitudinal perspective

The aim of this longitudinal study was to investigate how double-jump reaching task (DJRT) performance varies as a function of inhibitory load in children (6-12 years) with severe and moderate forms of developmental coordination disorder (s-DCD and m-DCD, respectively), compared with typically developing children (TDC). We tested 20 s-DCD, 43 m-DCD, and 192 TDC children, divided into younger (6-8 years) and older (9-12 years) age bands within each motor group. Children were tested twice, the second time after a 1-year follow-up, on two DJRT versions: standard (DJRT) and anti-jump (AJRT). Stimuli for each task appeared on a 42-inch touchscreen with a central home base and three target locations at - 20°, 0°, and 20°, 40 cm above the home base. For the DJRT, children lifted their index finger from the home base to the displayed target; 80% of trials were non-jump (to the central target) and 20% were jump where the target shifted left or right at lift-off. For the AJRT, they instead pointed to the contralateral location on anti-jump trials. Movement time difference measured the time difference between jump/anti-jump and no-jump trials. For the DJRT, there was no motor group effect, while older children made faster adjustments to jump targets. For the AJRT, the s-DCD group was consistently slower and had a significantly larger MTdiff score than both the m-DCD and TDC groups, regardless of age. The findings indicate that while cognitive-motor coupling improves with age in children with DCD, those with s-DCD have persistent difficulties.