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Updated: Sep 15, 2025
Dynamic Digital Biomarkers of Motor and Cognitive Function in Parkinson's Disease
Published on: July 24, 2019
REM density in Parkinson's disease: association with motor, cognitive, autonomic function, and dopaminergic
Andrew Dagay1,2, Shlomit Katzav2,3,4, Noa Elisha4
1Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
Abstract:
Recent work has shown that REM density, defined as the number of rapid eye movements per REM sleep minute, is decreased in people with Parkinson's disease (PD) and is associated with greater bradykinesia, suggesting a motor component. This study explored the association of REM density with gait, cognitive function, and heart rate variability (HRV). Seventy-seven PD patients underwent overnight polysomnography. Gait was evaluated using wearable technology during preferred-speed walking and while walking with a cognitive task (dual tasking). Lower REM density was associated with poorer gait and mobility, particularly during dual-tasking and turning, but not with HRV. Patients taking evening slow-release dopaminergic medication showed higher REM density compared to drug-naïve patients or those on daytime medication. These findings highlight the role of motor and cognitive functions in the generation of rapid eye movements in PD. Administration of evening medications appears to improve REM density, likely by alleviating motor control deficits.
Insights
Parkinson's disease patients with lower REM density exhibit poorer gait and mobility, especially during complex tasks. Evening medication may improve REM density by addressing motor deficits.
Area of Science:
- Neurology
- Sleep Medicine
- Movement Disorders
Background:
- REM density is reduced in Parkinson's disease (PD), correlating with bradykinesia.
- This suggests a potential link between REM sleep and motor function in PD.
Purpose of the Study:
- To investigate the relationship between REM density and gait, cognitive function, and heart rate variability (HRV) in PD patients.
- To explore the influence of dopaminergic medication timing on REM density.
Main Methods:
- Seventy-seven PD patients underwent overnight polysomnography to measure REM density.
- Gait and mobility were assessed using wearable sensors during walking and dual-tasking conditions.
- Heart rate variability (HRV) was also analyzed.
Main Results:
- Lower REM density correlated with impaired gait and mobility, particularly during dual-tasking and turning.
- No significant association was found between REM density and HRV.
- Patients on evening slow-release dopaminergic medication had higher REM density than drug-naïve or daytime-medicated patients.
Conclusions:
- REM density in PD is linked to motor and cognitive functions, especially gait control.
- Evening dopaminergic medication administration may enhance REM density, possibly by improving motor deficits.
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