Altered motor awareness in Parkinson's disease with progressive micrographia

Micrographia is a symptom characterized by abnormally small handwriting and is a common motor symptom in Parkinson's disease. Two subtypes-consistent micrographia (CM) and progressive micrographia (PM)-are thought to reflect distinct underlying mechanisms. CM has been linked to bradykinesia and often improves with dopaminergic treatment, whereas PM typically persists and may involve altered sensorimotor processing. However, the relative contributions of motor execution, feedback integration, and motor awareness to these subtypes remain unclear. This study investigated whether awareness of motor control differs between people with Parkinson's disease (PwP) and healthy controls (HC), and whether such differences are associated with micrographia subtypes. Forty-five PwP and twenty age-matched HC completed a handwriting task and a control detection task (CDT), which assesses the ability to distinguish self-generated from externally generated movements. Based on handwriting metrics, PwP were classified as having no micrographia, CM, or PM. CDT accuracy was significantly lower in PwP than in HC, with particularly reduced performance in individuals with PM. These findings suggest that PM is associated with reduced motor awareness, potentially involving altered prediction-feedback integration, and may inform the development of therapeutic approaches that complement dopaminergic treatment.