Effects of methylphenidate on quantitative measures of motor function: a systematic review

Introduction: Attention-deficit/hyperactivity disorder (ADHD) is a common mental disorder characterized by persistent patterns of inattention, hyperactivity, and impulsivity. Methylphenidate (MPH) is widely used to manage ADHD symptoms and improve cognitive and behavioral functioning; however, its effects on motor performance remain poorly understood. Most research has focused on cognitive and behavioral outcomes, with limited attention to objective measures of movement. Objective: This systematic review examined human studies that quantitatively assessed the influence of MPH on motor tasks and movement-related outcomes. Methods: Following PRISMA guidelines, a comprehensive search utilizing key terms was conducted using four databases: PubMed, APA PsycINFO, International Pharmaceutical Abstracts, and ProQuest Dissertations and Theses Global. Eligible studies were in English, included all age groups, included quantitative data on motor output, and employed observational, cohort, or cross-sectional designs. Additionally, studies must have compared MPH conditions to conditions without MPH. Covidence facilitated two-phase screening, and study quality was appraised using the Quality Assessment Tool for Quantitative Studies. Results: Of 1,314 titles and abstracts screened, 329 articles underwent full-text review, and 13 met inclusion criteria. Despite considerable methodological heterogeneity and variability of motor tasks, the overall evidence suggests that methylphenidate was associated with improvements in some quantitative motor outcomes, particularly measures of motor variability and steadiness. However, the effects were inconsistent across tasks and mean performance measures often showed no change. Conclusion: These findings highlight the need for future research to adopt standardized task protocols and consistent outcome measures, enabling more robust comparisons across studies and supporting meta-analytic synthesis.