Predictive Indicators of Kinematic Writing Ability in Patients with Parkinson’s Disease: Focusing on Cognition, Depression, and Motor Abilities

Objectives: Parkinson’s disease (PD) can affect not only motor abilities but also cognition and depression. The purpose of this study was to investigate the predictive indicators of kinematic writing ability in patients with Parkinson’s disease. Methods: Seventy-two subjects (47 patients with PD, 25 normal adults [NA]) performed tasks; including sentence writing along visual cues using software that could measure pen pressure, letter size, and writing speed. Results: Firstly, discriminant analysis showed that the writing speeds were good discriminators for the PD group. Secondly, the PD group showed positive correlation between the Korean version of the Montreal Cognitive Assessment (MoCA-K) score and pen pressure in the ‘writing within square blanks task’. They also showed a positive correlation between the Unified Parkinson’s Disease Rating Scale (UPDRS) score and letter size in the ‘free writing task’. The PD group showed a negative correlation between UPDRS score and writing speed in the ‘writing within square blank task’. Thirdly, the MoCA-K score showed significant explanatory power for pen pressure, and the UPDRS score showed significant explanatory power for the writing speed in the PD group. Conclusion: This study is significant in that it confirms the importance of considering various factors such as cognitive ability when examining the writing characteristics of patients with PD, which have been focused only on motor skills so far.