Exploring the Relationship between Tremor and Force Control in Parkinson's Disease: Insights from Wavelet Analysis

Abstract

Abstract This study investigates hand grip force control and tremor in Parkinson's disease (PD) patients with varying tremor conditions and severity levels, while considering the influence of visual feedback. A 40-second isometric constant grip force task was conducted on patients with unilateral, bilateral, and no tremors, across mild and moderate severities. Frequency domain analysis using Morlet wavelet transform was employed. The results revealed that grip strength did not significantly differ among tremor groups or severity levels. However, force accuracy, variability, and mean force were higher with visual feedback. Tremor intensity was greater in the unilateral tremor group, increasing with disease severity. Visual feedback effects on tremor characteristics varied with frequency bands and tremor profiles. Synchronicities were observed between force variability and tremor oscillations, with higher cross-wavelet power in the unilateral tremor group and moderate severity. Wavelet coherence showed higher values in the unilateral tremor group with no feedback in the 0-0.5 Hz range. This study provides valuable insights into force control and tremor characteristics, considering different tremor profiles and severity levels in PD. The findings have implications for tailoring therapeutic approaches for PD patients with distinct tremor profiles and severity levels.