Slow Wave Sleep and EEG Delta Spectral Power are Associated with Cognitive Function in Parkinson’s Disease

Abstract

Background: Cognitive and sleep dysfunction are common non-motor symptoms in Parkinson’s disease (PD). Objective: Determine the relationship between slow wave sleep (SWS) and cognitive performance in PD. Methods: Thirty-two PD participants were evaluated with polysomnography and a comprehensive level II neurocognitive battery, as defined by the Movement Disorders Society Task Force for diagnosis of PD-mild cognitive impairment. Raw scores for each test were transformed into z-scores using normative data. Z-scores were averaged to obtain domain scores, and domain scores were averaged to determine the Composite Cognitive Score (CCS), the primary outcome. Participants were grouped by percent of SWS into High SWS and Low SWS groups and compared on CCS and other outcomes using 2-sided t-tests or Mann-Whitney U. Correlations of cognitive outcomes with sleep architecture and EEG spectral power were performed. Results: Participants in the High SWS group demonstrated better global cognitive function (CCS) (p = 0.01, effect size: r = 0.45). In exploratory analyses, the High SWS group showed better performance in domains of executive function (effect size: Cohen’s d = 1.05), language (d = 0.95), and processing speed (d = 1.12). Percentage of SWS was correlated with global cognition and executive function, language, and processing speed. Frontal EEG delta power during N3 was correlated with the CCS and executive function. Cognition was not correlated with subjective sleep quality. Conclusion: Increased SWS and higher delta spectral power are associated with better cognitive performance in PD. This demonstrates the significant relationship between sleep and cognitive function and suggests that interventions to improve sleep might improve cognition in individuals with PD.

Reduced Regional NREM Sleep Slow-Wave Activity Is Associated With Cognitive Impairment in Parkinson Disease

“…We are aware of two previous studies that compared SWA to cognition in PD, with inconsistent findings. While a detailed sleep EEG analysis in 68 PD patients reported no association of cognitive impairment or decline with SWA (NREM delta power) (17), a recent study linked frontal SWA to global cognition in 32 PD patients (18). Compared to these studies, our analysis includes a larger sample (n = 140) of non-demented PD patients and 1-Hz-segmentation of regional SWA.…”

“…A detailed sleep EEG analysis reported no association of SWA with cognitive impairment in PD patients, but instead highlighted the importance of other sleep EEG alterations over posterior derivations (17). In contrast, a recent study linked SWA, a priori selected from frontal derivations, to global cognition, but the sample included only 32 PD patients (18). Therefore, the aim of our study was to clarify the relationship of SWA with cognition in PD by analyzing SWA and its regional variation in a larger sample of non-demented PD patients.…”

The top 100 most cited papers in insomnia: A bibliometric analysis

“…A growing body of research confirms that auditory stimulation ( 150 ), transcranial direct current stimulation ( 151 ), and medication ( 152 ) are all effective in improving memory function by enhancing slow waves of sleep ( 153 ). Slow-wave sleep is not only used for memory enhancement, but has also been widely used to improve cognitive function in patients with mental illness ( 154 , 155 ) and for sensory-motor recovery in stroke patients ( 156 ). Recent studies have shown that enhancing SWS in healthy individuals profoundly affects the connections between the endocrine and autonomic nervous systems ( 157 ), opening up a wide range of potential applications for enhancing SWS.…”

Characteristics of sleep structure in Parkinson's disease patients with hallucinations based on polysomnography

“…SWS is not only a major contributor to neurophysiological processes such as memory and attention, but it is also crucial for brain metabolite clearance ( 39 , 45 ). Moreover, deeper sleep relates to slower motor progression and better cognitive performance in PD ( 46 , 47 ).…”