Objective evaluation of attention-deficit/hyperactivity disorder medication effects using a load-cell-embedded chair in a simulated classroom

Abstract

Background: Attention-deficit/hyperactivity disorder (ADHD) is a prevalent neurodevelopmental condition in children. Treatment outcomes are assessed using established tools such as the Swanson, Nolan, and Pelham (SNAP-IV) scale and the Vanderbilt ADHD Diagnostic Rating Scale, which primarily rely on subjective reporting. In a previous pilot study, we used load cells to evaluate the effects of ADHD medication in patients receiving Ritalin immediate-release (IR). In the present study, we analyzed the effects of both Ritalin IR and ORADUR-Methylphenidate on the basis of changes in the average trajectory length (ATL) at different time points during a 15-min learning session in a simulated classroom.

Methods: A simulated classroom was constructed to replicate a real-world educational environment, featuring a desk and chair facing a large display screen. Load cells measuring mechanical force through material deformation were installed on each chair leg to monitor body movement. A total of 56 children with ADHD (boys: 49) were enrolled. They received Ritalin IR (n = 37; 10 mg/day orally) or ORADUR-Methylphenidate (n = 19; 22 mg/day orally) for 1 month. During assessment, participants were instructed to remain seated and watch an age-appropriate mathematics video. The ATL, derived through continuous load cell recordings, was calculated to quantify participants’ postural movement while seated as a representation of the mean distance of body movement over time. Parents and teachers also completed the SNAP-IV scale before and after participants began treatment.

Results: In the Ritalin IR group, posttreatment ATL values decreased significantly from 0.0318 ± 0.0191 to 0.0180 ± 0.0126 (43.40% reduction, p < 0.0001). Parent-reported SNAP-IV scores decreased from 37.75 ± 14.24 to 28.08 ± 16.94 (25.62% reduction, p < 0.0001), and teacher-reported scores decreased from 40.68 ± 17.66 to 24.36 ± 18.87 (40.12% reduction, p < 0.0001). In the ORADUR-Methylphenidate group, posttreatment ATL values decreased from 0.0431 ± 0.0277 to 0.0304 ± 0.0258 (29.47% reduction, p = 0.0140). Parent-reported SNAP-IV scores decreased from 40.75 ± 16.44 to 29.17 ± 17.80 (24.42% reduction, p = 0.0053), and teacher-reported scores decreased from 42.91 ± 18.04 to 25.64 ± 17.44 (40.22% reduction, p = 0.0082). Pretreatment ATL values progressively increased over time, particularly during the latter part of the video, whereas posttreatment values remained consistently low throughout the session.

Conclusion: The load cell–embedded smart chair may serve as an objective tool for assessing pharmacological treatment efficacy in children with ADHD, allowing researchers to effectively quantify hyperactivity and behavioral changes across time points.

Clinical trial number: Not applicable.

Keywords: Attention-deficit/hyperactivity disorder; Average trajectory length; Load cell; Smart chair; Therapeutic effect.

Fig. 1

Trajectory of the center of gravity during different movements. When the chair is empty, the center of gravity remains in the same position (orange dot). When the participant sways left and right, the trajectory shifts accordingly (yellow line). Swaying back and forth causes the trajectory to move in the same direction (green line). When the participant sits still, the trajectory changes only slightly (blue line)

Fig. 2

Trajectory of the center of gravity. Movement signals were measured before (blue) and after (orange) treatment in one patient with ADHD. Before treatment, the trajectory is dispersed. After treatment, the trajectory converges within a smaller area

Fig. 3

Comparison of temporal movement patterns before and after treatment by using slope-based analysis. The slope remains stable after treatment at different time intervals. By contrast, the slope increases significantly toward the end of the video session before treatment. (a) 2-minute, (b) 3-minute, (c) 4-minute, and (d) 5-minute time interval analyses

Fig. 4

Distribution of atl values across local and global segments shown by histogram. In both analyses, atl values significantly decreased after treatment, indicating reduced hyperactive movements and improved behavioral stability. (a) atl values aggregated in 5-minute intervals (0–5, 5–10, and 10–15 min) before and after treatment. (b) Global atl values comparing pre- and post-treatment sessions

Fig. 5

Comparison of temporal movement patterns before and after treatment using raw atl. atl values significantly decreased after treatment across different time intervals: (a) 2-minute, (b) 3-minute, (c) 4-minute, and (d) 5-minute analyses

Fig. 6

Comparison of relationship between percentage reduction in atl and percentage change in SNAP-IV scores. Scatter plots show that no significant correlations were observed in either analysis, suggesting that atl reduction reflects aspects of hyperactivity not fully captured by questionnaire-based ratings. (a) atl reduction and parent-reported SNAP-IV. (b) atl reduction and teacher-reported SNAP-IV