Reduced Cross-Frequency Coupling and Daytime Sleepiness in Obstructive Sleep Apnea Patients

Abstract

Obstructive sleep apnea (OSA) is associated with sleep-stage- and respiratory-event-specific sensorimotor cortico-muscular disconnection. The modulation of phase–amplitude cross-frequency coupling (PACFC) may influence information processing throughout the brain. We investigated whether sleep-stage-specific PACFC is impaired at the sensorimotor areas in OSA patients. C3 and C4 electrode EEG polysomnography recordings of 170 participants were evaluated. Different frequency band combinations were used to compute CFC modulation index (MI) to assess if MI differs between OSA and non-significant OSA patients in distinct sleep stages. We tested if the CFC-MI could predict daytime sleepiness in OSA. Theta–gamma CFC-MI at cortical sensorimotor areas was significantly reduced during all sleep stages; the delta–alpha CFC-MI was significantly reduced during REM and N1 while increasing during N2 in patients with respiratory disturbance index (RDI) > 15/h compared to those with RDI ≤ 15/h. A sleep stage classification using MI values was achieved in both patient groups. Theta–gamma MI during N2 and N3 could predict RDI and Epworth Sleepiness Scale, while delta–alpha MI during REM predicted RDI. This increase in disconnection at the cortical sensorimotor areas with increasing respiratory distress during sleep supports a cortical motor dysfunction in OSA patients. The MI provides an objective marker to quantify subjective sleepiness and respiratory distress in OSA.

Effects on resting‐state EEG phase‐amplitude coupling in insomnia disorder patients following 1 Hz left dorsolateral prefrontal cortex rTMS

“…The frontal cortex is a key node in arousal circuitry and is involved in multiple neuronal levels of metabolites such as corticosterone, adrenocorticotropic hormone, or thyrotropin. Our results are consistent with those of a previous study on sleep disorders, in which patients with obstructive sleep apnea had significantly lower theta‐gamma PAC (Gouveris et al, 2022 ). Theta rhythm is a marker of sleepiness during wakefulness and early phases of spontaneous sleep.…”

“…Our results are consistent with those of a previous study on sleep disorders, in which patients with obstructive sleep apnea had significantly lower theta-gamma PAC (Gouveris et al, 2022). Theta rhythm is a marker of sleepiness during wakefulness and early phases of spontaneous sleep.…”

“…It constitutes a flexible mechanism for combining information across different temporal scales within local cortical networks and plays a functional role in the execution of cognitive functions (Kikuchi et al, 2017 ; Malinowska & Boatman‐Reich, 2016 ; Reinhart & Nguyen, 2019 ; Seymour et al, 2017 ; Spyropoulos et al, 2018 ). Concerning sleep disorders, patients with obstructive sleep apnea had significantly lower theta–gamma PAC in the sensorimotor cortex at all sleep stages (Gouveris et al, 2022 ). Moreover, one study used PAC and amplitude‐amplitude coupling (AAC) to classify seven sleep disorders with 74% accuracy (Dimitriadis et al, 2021 ).…”

Drug-Induced Sleep Endoscopy Findings and Hypoglossal Nerve Stimulation Therapy Outcomes

“…ESS seems to be strongly affected by personal structure. From a pathophysiological neurophysiologic point of view and on the basis of emerging evidence, brain activity at the sensorimotor cortex of OSA patients may capture some of the features that are associated with excessive daytime sleepiness in these patients [ 45 ]. In accordance with such evidence, a correlation between the ESS score and several questionnaires testing for depression was observed [ 43 ].…”

Phase-Amplitude Coupling Localizes Pathologic Brain with Aid of Behavioral Staging in Sleep

“…Normal physiology of information transfer supported by PAC involves slow oscillations coupled with sleep spindles, which are in turn supported by coupling to high gamma or ripple bursts. In human epilepsy however, it has been postulated that this normal physiology is disrupted in seizure onset zones [ 28 , 39 , 40 ]. To date, little work has been carried out exploring PAC in the context of sleep and epilepsy.…”