Neural substrates underlying progressive micrographia in Parkinson's disease.
Shigenori Kanno1, Mayumi Shinohara1, Kasumi Kanno1
1Department of Behavioural Neurology and Cognitive Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Japan.
Brain and Behavior
|June 20, 2020
Summary
Progressive micrographia in Parkinson's disease (PD) is linked to distinct brain metabolism changes. Free writing issues involve the cingulate cortex, while copying problems relate to the occipital gyrus, impacting handwriting in PD patients.
Area of Science:
- Neuroscience
- Neurology
- Medical Imaging
Background:
- Micrographia, characterized by progressively smaller handwriting, is a common yet poorly understood symptom in Parkinson's disease (PD).
- The specific neural mechanisms driving micrographia development in PD patients are not well-established.
- Understanding these neural substrates is crucial for developing targeted interventions.
Purpose of the Study:
- To investigate the neural substrates underlying micrographia in Parkinson's disease patients.
- To differentiate the neural correlates of micrographia during free writing versus copying tasks.
- To identify brain regions with altered glucose metabolism associated with micrographia in PD.
Main Methods:
- Conducted handwriting tests (free writing and copying) on 40 PD patients and 20 healthy controls.
- Measured letter sizes during handwriting tasks.
- Utilized resting-state 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) to assess cerebral glucose metabolic rate in PD patients and 14 healthy controls.
Main Results:
- Progressive micrographia (PM) was observed in 15% of PD patients during free writing and 17.5% during copying.
- PD patients with PM during free writing showed reduced glucose metabolism in the right anterior cingulate cortex (including the rostral cingulate motor area).
- PD patients with PM during copying exhibited hypometabolism in the right superior occipital gyrus (including V3A).
Conclusions:
- Progressive micrographia in free writing in PD may stem from impaired monitoring of handwriting movements.
- Progressive micrographia during copying in PD appears related to a lack of visual feedback cues.
- Distinct neural regions are implicated in different types of micrographia in Parkinson's disease.
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