Association of Hypoxia Measured by Oxygen Desaturation Index (ODI) in OSA with Delis-Kaplan Executive Function System (D-KEFS) Tests in Middle-Aged and Older Adults

Abstract

Objective: This study aims to study the cognitive profile, in particular, executive function, and structural changes of the brain in obstructive sleep apnea (OSA) with regards to the degree of hypoxia and the characteristics of hypoxia in middle-aged and older adults. Method: Newly diagnosed moderate or severe OSA patients from King Chulalongkorn Memorial Hospital, Thailand were recruited. Respiratory parameters from the polysomnography, neuropsychological test results, and MRI brain of each participant were obtained. Results: Seventeen OSA patients were included in the study, 8 (47%) men and 9 (53%) women. The median age was 57 years and the median AHI was 60.6. There was no correlation between cognitive test scores in any domain with parameters of hypoxia. There was no correlation between cortical thickness with parameters of hypoxia. Participants were then classified as having either severe or mild hypoxia based on parameters of hypoxia. Cortical thickness analysis comparing between the severe and mild group of each hypoxic feature revealed two clusters of cortical thinning at the right inferior frontal gyrus and right inferior parietal gyrus in the severe desaturation group and a cluster of cortical thinning at the superior parietal gyrus in the high oxygen desaturation index group. There was no difference in cognitive function or white matter integrity between groups. Conclusion: A higher degree of hypoxia in OSA is associated with an early change of gray matter in the frontal and parietal regions.