Altered Motor Awareness in Parkinson's Disease with Progressive Micrographia

Micrographia, characterized by abnormally small handwriting, is a common motor symptom in Parkinsons disease (PD), and has been classified into consistent micrographia (CM) and progressive micrographia (PM), which may reflect different underlying mechanisms. However, the relative contributions of motor execution and sensorimotor processing to these subtypes remain unclear. In this study, forty-five people with Parkinsons disease (PwP) and twenty age-matched healthy controls (HCs) completed a handwriting task and a control detection task (CDT) assessing the ability to distinguish self-generated from externally generated movements. PwP were classified based on handwriting metrics as showing no micrographia, CM, and/or PM. CDT accuracy was significantly lower in PwP than in HCs (p < 0.01) and was particularly reduced in PwP with PM (p < 0.01). These findings indicate that PM is associated with impaired motor awareness, suggesting altered sensorimotor integration as a characteristic feature of this subtype.