Obstructive Sleep Apnea Syndrome Disrupts Glymphatic-Related Physiological Brain Pulsations

Abstract

BackgroundObstructive sleep apnea (OSA) affects over one billion people and increases neurodegenerative risk. Brain vasomotor, respiratory, and cardiac pulsations are thought to drive glymphatic clearance during sleep, yet OSAs effect on these pulsations remains poorly understood. MethodsWe studied 20 healthy controls (HC; 39.7{+/-}8.0 y) and 12 patients with OSA (PWOSA; 53.0{+/-}11.0 y) using a four wavelength (690-980 nm) functional near-infrared spectroscopy (fNIRS) measuring oxygenated, deoxygenated and total hemoglobin, water and cerebrospinal fluid (HbO, HbR, HbT, H2O, CSF). Polar devices provided heart rate variability (HRV). Spectral power, coherence and phase transfer entropy analysis was performed for very low frequency (VLF), respiratory, and cardiac bands from 30 min sleep segments and event-based whole-night analysis assessed autonomic responses. ResultsOSA patients exhibited lower fNIRS spectral entropy for HbO, HbT, H2O & CSF (p0.73). ConclusionsOSA reorganizes cortical pulsatile dynamics - reducing complexity, amplifying low frequency power and suppfdsfsdfsdfsdisrupting directed coupling. This state may compromise sleep-related glymphatic clearance. fNIRS-based spectral analysis offers a promising bedside tool for monitoring brain pulsatility.