Accepted for/Published in: JMIR mHealth and uHealth
Date Submitted: Nov 20, 2024
Date Accepted: Sep 25, 2025
Dynamic Assessment of Fine Motor Control and Vocalization in Parkinson’s Disease Through Smartphone Application: Cross-Sectional Study of Time–Severity Interaction Effects
ABSTRACT
Background:
Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by motor and non-motor symptoms that worsen over time, significantly impacting quality of life.
Objective:
This study aimed to quantitatively assess the time-disease severity interaction effect in Parkinson’s disease (PD) motor symptoms using a smartphone-based application to evaluate finger-tapping dysrhythmia and vocal changes in persons with varying PD severity and healthy adults.
Methods:
This was an exploratory, cross-sectional pilot study. Disease severity in persons with PD was assessed using the modified Hoehn & Yahr Scale, Voice Handicap Index, and Unified Parkinson’s Disease Rating Scale (UPDRS). A smartphone application was used to conduct finger-tapping tasks, sustained phonation, and rapid syllable repetition tasks. The total tap counts, tap-to-tap variability, and vocal parameters (loudness, jitter, shimmer, and repeat counts) were analyzed. Time-severity interactions were examined using linear mixed models (LMM).
Results:
Twenty persons with PD and 20 healthy adults were included in this study. Persons with PD showed significantly worse motor and vocal performance than healthy adults, with significantly higher dysrhythmia, and worse jitter, shimmer, jitter and shimmer variability, and fewer repeat counts. Persons with PD also showed an earlier onset of dysrhythmia than healthy adults during finger-tapping tasks. LMM confirmed significant time-severity interaction effects in sustained phonation tasks (loudness, jitter, and shimmer) and syllable repeat variability. Smartphone-based quantitative analysis successfully captured the earlier onset of dysrhythmia and vocal control deficits in persons with higher UPDRS Part III scores.
Conclusions:
This study highlights that individuals with more severe PD experience earlier-onset dysrhythmia and vocal control deficits capturable with a few minutes of smartphone-based assessment. Such an application may provide an effective tool for the continuous monitoring of timelapse change of PD symptoms, enabling more precise prognostication and timely interventions.
Citation
Request queued. Please wait while the file is being generated. It may take some time.
Copyright
© The authors. All rights reserved. This is a privileged document currently under peer-review/community review (or an accepted/rejected manuscript). Authors have provided JMIR Publications with an exclusive license to publish this preprint on it's website for review and ahead-of-print citation purposes only. While the final peer-reviewed paper may be licensed under a cc-by license on publication, at this stage authors and publisher expressively prohibit redistribution of this draft paper other than for review purposes.