This study aimed to investigate the differences in fine motor and coordination skills between boys with attention-deficit/hyperactivity disorder (ADHD) and typically developing (TD) boys and the effect of methylphenidate (MPH) in boys with ADHD.
Fourteen boys aged 7-12 years who were diagnosed with ADHD and previously treated with MPH were instructed to tap their thumbs and index fingers together repetitively for 10 s after attaching magnetic sensors. The participants executed “in-phase” and “anti-phase” tapping. A two-way analysis of variance for comparing boys with ADHD and TD boys and the paired t-test to investigate the effect of MPH between sessions with and without MPH were performed.
Boys with ADHD showed a significantly lower “number of taps” and a significantly higher “average of local maximum distance” than TD boys. “Energy balance” was significantly lower in ADHD boys than in TD boys. MPH caused a significant difference in the “standard deviation (SD) of phase difference” in “anti-phase tapping.”
Our studies indicated that finger-tapping movements in boys with ADHD tended to be significantly wider and fewer than those in TD boys, and MPH may improve the phase difference of bimanual fine motor coordination skills in boys with ADHD who are above 1.0 SD. The results should be interpreted with caution because we conducted statistical tests for many outcomes and groups without considering the multiplicity factor from an exploratory perspective.

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