Longitudinal Monitoring of Digitized Cursive Writing in People with Parkinson’s Disease Shows Increased Variability in Absolute Jerk and Decreased Writing Duration in Those with Freezing of Gait
Jennie Lance1, Lakshmi Pillai2, Tuhin Virmani2
1College of Medicine, 2Department of Neurology, University of Arkansas for Medical Sciences
Objective:
To determine if handwriting declines faster in People with Parkinson’s disease (PwPD) with freezing of gait (FOG).
Background:
Motor Blocks (MB) commonly occur in PwPD. While FOG is the most studied MB manifestation, MB in handwriting have also been reported. Whether MB in handwriting precede those in gait is unclear, and how handwriting changes over time in people with or without MB is not well studied.
Design/Methods:
PwPD wrote “There are earthquakes in California” three times in cursive using an inking Pen (WaCOM) on paper overlaying a digitizing WaCOM Intous pro tablet (Portland, OR). Data was gathered at 6 months intervals and analyzed using Movalyzer software (Neuroscript, Tempe, AZ). The mean, variability (CV) and rate of change (delta) was calculated for 9 spatiotemporal variables. Group differences between those without (noFOG) and with FOG were determined using the Mann-Whittney U test.
Results:
29 PwPD (9 FOG and 20 noFOG) were analyzed. There were no significant differences between the two groups in age, disease duration, or levodopa dosing. Compared to noFOG, those with FOG had significantly lower mean absolute jerk (2340±3338 FOG vs. 3051±1872 noFOG, Z=-1.980, p=0.048) and lower CV absolute jerk (129.9±48.9 FOG vs. 292.6±68.0 noFOG, Z=-3.441, p=0.001) at their initial visits. Delta CV absolute jerk increased faster over time (28.4±48.9 FOG vs. -23.9±59.6 noFOG, Z=-2.498, p=0.012) while the sentence writing duration delta decreased faster over time (-1.1±4.7 FOG vs. 4.4±5.6 noFOG, Z=-2.216, p=0.027) in FOG compared to noFOG groups. The correlation between delta freezing severity (FOG-Questionnaire items 3-6) and delta CV absolute jerk was nearing significance (Kendall’s tau-b=0.269, p=0.065).
Conclusions:
Over time, PD FOG participants wrote faster with increased variability in writing jerkiness compared to noFOG participants. Further work is needed to determine if these spatiotemporal changes can lead to handwriting MB in PwPD or other clinical implications.
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