Characteristics of writing in parkinson's disease: Focused on pen pressure, letter size, and writing speed

Objectives: Movement disorders in Parkinson's disease (PD) can affect not only letter size but also pen pressure and writing speed. The purpose of this study was to investigate the characteristics of writing with focus on pressure, size, and speed in PD. Methods: Sixty-three subjects (38 in a PD group and 25 in a normal adult [NA] group) performed tasks involving drawing along dotted lines and sentence writing using a tablet PC, digital pen, and software that could measure pen pressure, stroke length, and duration. Results: In the task involving drawing along a dotted line, the PD group showed significantly slower writing speed compared with the findings in the NA group. Additionally, in the task involving sentence writing, the PD group showed significantly weaker pen pressure, smaller letter size, and slower writing speed compared with the NA group. Moreover, both groups showed a positive correlation between letter size and writing speed, but only the PD group showed a positive correlation between pen pressure and writing speed. Conclusion: Difficulty in motor control of strength, size, speed, etc. owing to PD is reflected in pen pressure, letter size, and writing speed when performing a writing task. Our results show an importance in measuring multiple factors such as pen pressure and writing speed in the characteristics of writing in PD, which has until now, has been focused only on letter size.