Quantitative Sleep Electroencephalogram in Parkinson’s Disease: A Case-Control Study

Abstract

Background: Sleep disorders are common in Parkinson’s disease (PD) and include alterations in sleep-related EEG oscillations. Objective: This case-control study tested the hypothesis that patients with PD would have a lower density of Scalp-Slow Wave (SW) oscillations and higher slow-to-fast frequencies ratio in rapid eye movement (REM) sleep than non-PD controls. Other sleep-related quantitative EEG (qEEG) features were also examined, including SW morphology, sleep spindles, and Scalp-SW spindle phase-amplitude coupling. Methods: Polysomnography (PSG)-derived sleep EEG was compared between PD participants (n = 56) and non-PD controls (n = 30). Following artifact rejection, sleep qEEG analysis was performed in frontal and central leads. Measures included SW density and morphological features of SW and sleep spindles, SW-spindle phase-amplitude coupling, and spectral power analysis in Non-REM (NREM) and REM. Differences in qEEG features between PD and non-PD controls were compared using two-tailed Welch’s t-tests, and correction for multiple comparisons was performed per the Benjamini-Hochberg method. Results: SW density was lower in PD than in non-PD controls (F = 13.5, p’ = 0.003). The PD group also exhibited higher ratio of slow REM EEG frequencies (F = 4.23, p’ = 0.013), higher slow spindle peak frequency (F = 24.7, p’ < 0.002), and greater SW-spindle coupling angle distribution non-uniformity (strength) (F = 7.30, p’ = 0.034). Conclusion: This study comprehensively evaluates sleep qEEG including SW-spindle phase amplitude coupling in PD compared to non-PD controls. These findings provide novel insights into how neurodegenerative disease disrupts electrophysiological sleep rhythms. Considering the role of sleep oscillatory activity on neural plasticity, future studies should investigate the influence of these qEEG markers on cognition in PD.

Effects of deep brain stimulation on quantitative sleep electroencephalogram during non-rapid eye movement in Parkinson’s disease

“…SW and spindle phase-amplitude coupling (PAC) promotes memory consolidation, and declines with physiological aging (Helfrich et al, 2018;Muehlroth et al, 2019). In the only prior study investigating SW-spindle PAC in PD, we found higher non-uniformity in SW-spindle coupling in PD patients compared to controls (Memon et al, 2023).…”

“…To detect slow waves (SW) and sleep spindles, EEG data without artifacts were processed using a custom MATLAB script that utilized validated algorithms previously employed in studies involving older adults ( Mölle et al, 2011 ; Staresina et al, 2015 ; Helfrich et al, 2018 ; Memon et al, 2023 ).…”

“…The subsequent sleep spindle characteristics were computed and averaged over all stage N2 epochs from the entire PSG recording: (1) density (number of events per minute), (2) amplitude (peak-to-peak, measured in microvolts), and (3) peak frequency (cycles per second, measured in Hz) for spindles (9–15 Hz), slow spindles (9–11 Hz), and fast spindles (12–15 Hz). The division into slow and fast frequency bins was based on our previous findings that demonstrated a higher slow spindle peak frequency in PD patients compared to non-PD controls ( Memon et al, 2023 ).…”

“…In contrast to N2 sleep, pertinent electrophysiological features of N3 sleep include both slow waves (SW, <1 Hz), which occur with lower density in PD patients and may be altered in morphology compared to controls ( Memon et al, 2023 ), and power in the delta frequency range (1.0–4.0 Hz). In prior work, we found a reduced SW density in a group of 56 PD patients compared to controls, but no difference in delta spectral power or SW morphological features including peak-to-peak amplitude and slope ( Memon et al, 2023 ). However, other studies have found conflicting results.…”