Functional connectivity in default mode network correlates with severity of hypoxemia in obstructive sleep apnea

• Published in: Brain and behavior Vol. 10; no. 12; pp. e01889 - n/a
• Main Authors: Chang, Ya‐Ting, Chen, Yung‐Che, Chen, Yung‐Lung, Hsu, Shih‐Wei, Yang, Feng‐Yueh, Lee, Chen‐Chang, Hsu, Po‐Yuan, Lin, Meng‐Chih
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01.12.2020; John Wiley and Sons Inc; Wiley
• Subjects: cognition; Cognitive ability; Dementia; Efficiency; Magnetic resonance imaging; Memory; neuroimaging; Original Research; Principal components analysis; Sleep apnea; cognition; neuroimaging
• ISSN: 2162-3279; 2162-3279
• DOI: 10.1002/brb3.1889

Introduction Obstructive sleep apnea (OSA)‐associated hypoxemia, sleep fragmentation, and cerebral vascular dysfunction are implicated in cognitive dysfunction. Functional connectivity within default mode network (DMN) is a possible mechanism underlying the cognitive impairment. The aim of this study was to investigate the impact of hypoxemia and sleep fragmentation on functional connectivity and on cognitive performance in patients with OSA. Methods Twenty‐eight patients with OSA were included (mean age = 58.0 ± 8.5 years). We correlated the functional connectivity in DMN with cognitive performances and further analyzed the relationship of functional connectivity in DMN with hypoxemia severity, as revealed by apnea‐hypopnea index (AHI), oxygen desaturation index (ODI), and nadir SaO2 (%), and with degree of sleep fragmentation, as shown by sleep efficiency and wake after sleep onset. Results Functional connectivity in DMN was associated with AHI, ODI, and nadir SaO2 (%) (p < .05) and was not associated with sleep fragmentation measures (p > .05). Functional connectivity that was associated with AHI, ODI, and nadir SaO2 (%) was in the areas of bilateral middle temporal gyri, bilateral frontal pole, and bilateral hippocampus and was positively correlated with Cognitive Abilities Screening Instrument (CASI) total score (ρ = 0.484; p = .012), CASI‐List‐generating, CASI‐Attention, and composite score of CASI‐List‐generating plus CASI‐Attention (p < .05). Conclusion Functional connectivity in DMN is implicated in impairment of global cognitive function and of attention in OSA patients. The functional connectivity in the DMN is associated with hypoxemia rather than with sleep fragmentation. The functional connectivity within the DMN was associated with hypoxemia severity, as revealed by apnea‐hypopnea index, oxygen desaturation index, and nadir SaO2 (%), rather than with degree of sleep disruption, as shown by sleep efficiency and wake after sleep onset.