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Updated: Jun 14, 2026

Dynamic Digital Biomarkers of Motor and Cognitive Function in Parkinson's Disease
10:28

Dynamic Digital Biomarkers of Motor and Cognitive Function in Parkinson's Disease

Published on: July 24, 2019

Altered motor awareness in Parkinson's disease with progressive micrographia

Hiroyuki Hamada1, Kyohei Mikami2, Wen Wen3

  • 1Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8563, Japan.

Neuropsychologia
|June 12, 2026
PubMed

Insights

Progressive micrographia (PM) in Parkinson's disease is linked to reduced motor awareness. This may involve altered sensory feedback processing, suggesting new therapeutic targets beyond standard dopaminergic treatments.

Area of Science:

  • Neuroscience
  • Movement Disorders
  • Motor Control

Background:

  • Micrographia, characterized by small handwriting, is a common motor symptom in Parkinson's disease (PD).
  • Two subtypes, consistent micrographia (CM) and progressive micrographia (PM), are proposed to have distinct mechanisms.
  • While CM is linked to bradykinesia and improves with dopaminergic treatment, PM persists and may involve altered sensorimotor processing, but its relation to motor awareness is unclear.

Purpose of the Study:

  • To investigate differences in motor control awareness between people with Parkinson's disease (PwP) and healthy controls (HC).
  • To determine if these differences are associated with micrographia subtypes (CM and PM).

Main Methods:

  • Forty-five PwP and twenty age-matched HC performed a handwriting task and a control detection task (CDT).
  • The CDT assesses the ability to distinguish self-generated from externally generated movements.
  • PwP were classified into no micrographia, CM, or PM groups based on handwriting metrics.

Main Results:

  • Healthy controls (HC) demonstrated significantly higher accuracy on the CDT compared to people with Parkinson's disease (PwP).
  • Individuals with progressive micrographia (PM) exhibited particularly reduced performance on the CDT.
  • Lower CDT accuracy in PwP suggests impaired motor awareness.

Conclusions:

  • Progressive micrographia (PM) in Parkinson's disease is associated with reduced motor awareness.
  • This deficit may stem from altered prediction-feedback integration in sensorimotor processing.
  • Findings suggest potential for therapeutic strategies targeting motor awareness to complement dopaminergic treatments for PM.
Keywords:
DysgraphiaHandwritingInternal modelMotor controlSensorimotor integration

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