Hypoxia Affects Glymphatic Efficiency: Assessing Glymphatic Disruption in Obstructive Sleep Apnea Using Near-infrared Spectroscopy
Sujasha Gupta1, John werner2, William Coon3, Franck Amyot4, Angeliki Pollatou1, Angelica Lee1, Elizabeth Metzger1
1Uniformed Services University, 2Neurology, Uniformed Services University, 3JHU applied physics lab, 4Walter Reed National Military Medical Center
Objective:
This study aimed to determine if OSA impairs cerebral fluid dynamics, measured via the flux changes between NIRS-derived HbO and water concentrations, as a novel surrogate marker for blunted glymphatic clearance during sleep.
Background:
Near-Infrared Spectroscopy (NIRS) is a non-invasive imaging technique used to monitor cerebral oxygenation and hemodynamic changes. Obstructive Sleep Apnea (OSA) causes recurrent airway obstruction and disrupts oxygen homeostasis, leading to neurocognitive and cardiovascular dysfunction. We explored a novel surrogate measure of glymphatic clearance in OSA, focusing on sleep-related fluctuations in oxyhemoglobin (HbO) and water dynamics, using flux differences between water and HbO as proxies for flow changes.
Design/Methods:
NIRS measured changes in HbO and water concentrations during sleep in OSA participants (N=9) and healthy controls (N=18). Data were preprocessed to remove motion artifacts, bandpass filtered (0.005–0.2 Hz), and analyzed using the modified Beer-Lambert law to extract phase and amplitude. Statistical analyses assessed differences in concentration modulation between HbO and water.
Results:
Healthy individuals exhibited distinct water concentration changes across sleep stages, which were significantly blunted in the OSA group. Post-hoc tests showed significant amplitude differences during N3 and Wake in healthy participants (P<0.0001, d=1.22), but no differences in the OSA group. While HbO concentration was modulated across sleep stages in controls, this modulation was also blunted in the OSA group. Notably, HbO concentration showed a remarkable decrease during REM sleep specifically in OSA positive participants.
Conclusions:
Disrupted water concentration changes in OSA subjects indicate impaired glymphatic function, particularly during deep sleep, which is critical for waste clearance. The reduced HbO concentration during REM sleep in OSA subjects suggests severe nocturnal oxygen desaturation and implies potential systemic and neurological impacts.
Disclaimer: Abstracts were not reviewed by Neurology® and do not reflect the views of Neurology® editors or staff.