Beyond RBD: covert REM sleep abnormalities in Parkinson's disease

Area of Science:

• Neuroscience
• Sleep Medicine
• Neurology

Background:

• REM sleep behavior disorder (RBD) is a prodromal marker for Parkinson's disease (PD).
• It is unclear if RBD represents the full extent of REM sleep pathology in early PD.

Purpose of the Study:

• To investigate REM sleep abnormalities beyond clinically diagnosed RBD in early, drug-naïve PD patients.
• To assess the relationship between REM sleep patterns, generalized motor learning (GML), and disease progression.

Main Methods:

• Overnight polysomnography with high-density EEG (256 channels) in 25 early PD patients and 23 controls.
• Assessment of REM sleep without atonia (RSWA) and spectral analysis during REM sleep.
• Evaluation of sleep's impact on overnight generalized motor learning (GML).

Main Results:

• PD patients showed elevated RSWA, with 36% meeting criteria for excessive RSWA (PD+RSWA).
• Increased occipital-parietal theta activity during REM sleep in PD+RSWA correlated with disease progression.
• Sleep benefited GML in all participants, but REM sleep duration negatively correlated with GML benefits in PD patients, especially PD+RSWA.

Conclusions:

• Subtle REM sleep disruptions, including excessive RSWA and altered theta activity, are present in early PD, extending beyond overt RBD.
• These REM sleep abnormalities are associated with disease progression and impaired sleep-dependent motor learning.
• REM sleep disruptions may serve as early neurophysiological markers for PD and potential therapeutic targets.