Effects of Methylphenidate and Atomoxetine Treatment on Improvement of Motor Coordination in Children With Attention-Deficit/Hyperactivity Disorder

Objective To investigate the effects of methylphenidate and atomoxetine treatment on motor coordination in children with attentiondeficit/hyperactivity disorder (ADHD). Methods In this single-site, open-label, naturalistic follow-up study, 157 children (7.6 +/- 1.4 years; 139 males) with ADHD were recruited between March 2015 and May 2020 from the Department of Psychiatry, Asan Medical Center, and treated for 12 weeks with methylphenidate (n=48) or atomoxetine (n=109). Children completed the Advanced Test of Attention (ATA), and caregivers completed the ADHD Rating Scale (ARS) questionnaire and Developmental Coordination Disorder Questionnaire (DCDQ) at baseline and at 12 weeks. Paired t-tests, a mixed-effects model, and linear regression were used to compare treatment groups and assess factors influencing motor coordination changes. Results Methylphenidate and atomoxetine resulted in significant improvement in DCDQ fine motor/handwriting, general coordination, and total scores over 12 weeks. Fine motor/handwriting had a significant main effect for time (F-1=16.64, p<0.001, eta(2 )=0.097); however, the interaction effect between group and time was not significant (F-1=0.24, p=0.625, eta(2)=0.002). Changes in parent-reported ARS inattention scores ((beta=-0.174, p=0.029) and auditory commission errors of ATA ((beta=0.191, p=0.022) were significantly associated with changes in fine motor/handwriting. Additionally, changes in parent-reported ARS inattention scores ((beta=-0.177, p=0.034) and rater-reported ARS inattention scores ((beta=-0.198, p=0.017) were significant predictors of improvements in general coordination in separate models. Conclusion Methylphenidate and atomoxetine had a positive effect on motor coordination in children with ADHD. Improvement in motor coordination was associated with ADHD symptom improvement.