Impaired motor inhibition in developmental coordination disorder.

This study aimed to evaluate the 'inhibitory deficit' hypothesis of developmental coordination disorder (DCD). We adopted a multifaceted approach, investigating two distinct, yet complimentary facets of motor inhibition: action restraint and action cancellation. This was achieved using carefully constructed versions of the 'Go/No-go' and 'Stop-signal' tasks, respectively. The sample comprised 11 young adults with DCD aged between 18 and 30 years of age and 11 typically developing, age-matched controls. Participants completed both the 'Go/No-go' and 'Stop-signal' tasks to assess action restraint and action cancellation respectively. Individuals with DCD were less efficient than their typically developing peers at performing both action restraint and action cancellation, indicated by significantly reduced action restraint efficiency index scores on the 'Go/No-go' task and a trend towards longer stop-signal reaction times on the 'Stop-signal' task. This work clarifies disparate evidence speaking to the integrity of action restraint in DCD and provides the first account of action cancellation in DCD using a purpose-built measure. In support of the inhibitory deficit hypothesis of DCD, our results suggest that young adults with DCD experience broad difficulties with engaging inhibitory mechanisms during motor behaviour.