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Hypoxic Load and Average Oxygen-Saturation During Sleep and Wake Are Associated With Cognitive Function in
K Thorisdottir1,2, T Leppänen3,4,5, H Hrubos-Strøm6,7
1Reykjavik University Sleep Institute, School of Technology, Reykjavik University, Reykjavik, Iceland.
Journal of Sleep Research
|July 3, 2025
Summary
Obstructive sleep apnea (OSA) severity impacts cognition more through oxygen levels than AHI. Lower oxygen during sleep and wakefulness significantly affects memory, vigilance, and processing speed.
Area of Science:
- Neurology
- Sleep Medicine
- Pulmonology
Background:
- Obstructive sleep apnea (OSA) is linked to cognitive deficits.
- The apnea-hypopnea index (AHI) is a standard OSA severity measure.
- Hypoxic events and oxygen saturation (SpO2) may also impact cognition.
Purpose of the Study:
- To determine which OSA severity parameters best predict cognitive performance.
- To investigate the role of wake SpO2 in cognitive function.
- To compare the predictive power of hypoxic load versus AHI for cognitive deficits.
Main Methods:
- Sixty-one participants with OSA underwent a three-night polysomnography (PSG).
- Cognitive performance was assessed using a digital neurocognitive battery.
- Oxygen saturation-based PSG parameters and AHI were analyzed as predictors.
Main Results:
- Oxygen saturation-based OSA parameters, not AHI, predicted immediate recall, vigilance, and processing speed.
- Greater hypoxic severity predicted slower processing speed.
- Lower average sleep SpO2 most strongly predicted immediate recall and vigilance.
- Lower wake SpO2 was associated with reduced vigilance.
Conclusions:
- Hypoxic load parameters are stronger predictors of cognitive deficits in OSA than AHI.
- Concurrent assessment of sleep and wake SpO2 is recommended for a comprehensive understanding of OSA's cognitive impact.
- Current OSA severity metrics may not fully capture the neurological consequences of the condition.
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