Respiratory event-related physiological biomarkers and cognitive performance in obstructive sleep apnoea

BACKGROUND: respiratory event-related electroencephalography (EEG) activity and autonomic responses) and the risk of cognitive impairment. METHODS: ) from the Canadian Sleep and Circadian Network observational cohort were studied. Brain Response to Event (BReTE) was derived from EEG power (defined as mean (median post-event power/median pre-event power) (frequency range: 0.5-50 Hz)) for each individual. Event-related autonomic responses were measured by heart rate response to events (ΔHR: the difference between maximum post-event heart rate and minimum heart rate during event) and photoplethysmography (PPG)-derived vasoconstriction activity (event-related area and depth of PPG decline). Cognitive performance was assessed using the Montreal Cognitive Assessment (MoCA), Wechsler Digit Symbol Coding (DSC) and Rey Auditory Verbal Learning Test-Delayed Recall (RAVLT-DR). Multiple logistic regression examined the independent associations between biomarkers and outcomes. RESULTS: We studied 537 individuals (42% female) with a median age of 55 years. In fully adjusted models, each 1sd decrease in BReTE was associated with higher odds of poor cognitive performance indicated by MoCA <26 (OR 1.42, 95% CI 1.13-1.79; p=0.003), DSC <25th percentile (OR 1.35, 95% CI 1.02-1.84; p=0.04) and RAVLT-DR <25th percentile (OR 1.50, 95% CI 1.13-2.02; p=0.007). Additionally, those with low ΔHR compared to the mid-range group were at increased risk of poor cognitive performance. Vasoconstriction indices were not associated with cognitive performance. CONCLUSION: Blunted EEG and heart rate responses to respiratory events are linked to poorer cognitive performance in OSA, highlighting the value of EEG in identifying individuals at risk for cognitive impairment.