Psychomotor intervention to improve handwriting skills in children with ADHD: A single-case experimental design with direct inter-subject and systematic replications

Dysgraphia is highly prevalent in children with attention deficit hyperactivity disorder (ADHD) and adversely affects academic and developmental trajectories. To date, no study has rigorously examined the effects of a training program on handwriting quality in this specific population. Our objective was thus to develop an innovative program - we entitled PRO-PEN - and to evaluate its effects. We planned a multiple-baseline design across participants from grade 3-5, with direct inter-subject and systematic replications. Children of Group 1 (n = 4) were diagnosed with ADHD. Systematic replication was conducted in a second group of participants (Group 2, n = 4) with a diagnosis of developmental coordination disorder in addition to ADHD. The primary assessment focused on quality of handwriting. Generalization measures evaluated diverse neuropsychological and behavioural domains. In Group 1, effect sizes regarding handwriting quality were large (Tau(s) > .60). Improvement was also observed for children of Group 2 (Tau(s) > .50). Importantly, the positive effects persisted three months after the end of the training. Generalization effects extended beyond handwriting sphere. Therefore, PRO-PEN can be considered a promising training program for improving handwriting quality in ADHD, with a possible impact on wide cerebral regulation loops underpinning both handwriting and other neuropsychological and behavioural domains.