## 5 Discussion  
In this study, we found that the variance values along the \(y\)- and \(z\)-axes of the accelerometer significantly decreased in patients with ADHD after the use of methylphenidate, an ADHD medication. Thus, the variance value may be a useful and objective marker for evaluating therapeutic effects of ADHD medication use in patients with ADHD. The SNAP questionnaire were originally developed to assess ADHD symptoms according to the DSM-III [19; 20]. Although several studies have demonstrated that the SNAP score has high validity and reliability [21; 22; 23], one study found that interrater agreement between parents and teachers is poor [5]. In addition, the parents' ratings of inattention and hyperactivity/impulsivity are good predictors for research but not for clinical diagnosis. Regarding teacher ratings, only hyperactivity/impulsivity scores are good predictors for research and clinician diagnosis [22]. The discrepancies in the SNAP scores by parents and teachers for patients with ADHD can lead to diagnostic uncertainty. We used a smart watch equipped with an accelerometer to record the activity of patients with ADHD and noted \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Axis\_X Var Reduction** & **Axis\_Y Var Reduction** & **Axis\_Z Var Reduction** \\  & **Percentage** & **Percentage** & **Percentage** \\ \hline Teacher SNAP (I) & \(-\)0.0227 & 0.0917 & 0.3565 \\ Reduction Percentage & 0.2881 & 0.6053 & 0.4605 \\ Teacher SNAP (O) & \(-\)0.2331 & \(-\)0.0778 & \(-\)0.0373 \\ Reduction Percentage & & & \\ \hline \hline \end{tabular} (I): inattentive; (H): hyperactive; (O): oppositional defiant.  
\end{table} 
Table 3: Correlation coefficient between reductions of SNAP subscales and variance values across three axes. Figure 2: Correlation between decreased Swanson, Nolan, and Pelham (SNAP) questionnaire scores and reduction in variance values. Some patients with ADHD exhibited discrepancy between decreased SNAP scores and reduced accelerometer variance values of along the three axes. significant decreases in variance values of accelerometer recordings. This method is recommended as an objective and convenient tool for evaluating the therapeutic effects of ADHD medications. Electronic devices have been used to detect motor function in several medical conditions. [PERSON] et al. used smartphones to detect gait variability in patients with Parkinson's disease (PD) and found increased gait variability in patients with PD compared with healthy controls [24]. [PERSON] et al. analyzed the differences in variance of performance in the Extended Timed Up and Go test in frail and nonfrail elderly people by using smartphones. The authors reported that accelerometry values for the frail elderly people were lower than those for the nonfrail elderly people [25]. In patients with idiopathic normal pressure hydrocephalus (iNPH), a body-worn gyroscopic system was used to detect gait and postural stability. The results demonstrated that the patients with iNPH had significantly higher trunk sway compared with healthy elderly patients, specifically in standing tasks [26]. Here, we used an accelerometer to evaluate the therapeutic effects of an ADHD medication, methylphenidate, in patients with ADHD and noted that the variance values along the \(y\)- and \(z\)-axes significantly decreased after one month of methylphenidate use. Accordingly, a smart watch equipped with an accelerometer is an effective alternative method for evaluating the treatment effects of ADHD medications. Of the ADHD subtypes, the most prevalent are ADHD-C and ADHD-H (78.0-81.7%), followed by ADHD-I (18.3-22.0%) [27; 28; 29]. Here, 8 of 10 patients had ADHD-C, and therefore, most of the recruited patients demonstrated hyperactive symptoms. Accordingly, we noted a moderate-to-strong correlation between decreased SNAP hyperactive subscale scores and variance values of the \(y\)-axis of the accelerometer. This study has some limitations.