Impaired Glymphatic System Actions in Obstructive Sleep Apnea Adults

Bhaswati Roy; Alba Nunez; Ravi S Aysola; Daniel W Kang; Susana Vacas; Rajesh Kumar

doi:10.3389/fnins.2022.884234

Impaired Glymphatic System Actions in Obstructive Sleep Apnea Adults

Front Neurosci. 2022 May 6:16:884234. doi: 10.3389/fnins.2022.884234. eCollection 2022.

Authors

Bhaswati Roy¹, Alba Nunez¹, Ravi S Aysola², Daniel W Kang², Susana Vacas¹, Rajesh Kumar^{1

3

4

5}

Affiliations

¹ Department of Anesthesiology and Perioperative Medicine, University of California, Los Angeles, Los Angeles, CA, United States.
² Department of Medicine, University of California, Los Angeles, Los Angeles, CA, United States.
³ Department of Radiology, University of California, Los Angeles, Los Angeles, CA, United States.
⁴ Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States.
⁵ Brain Research Institute, University of California, Los Angeles, Los Angeles, CA, United States.

Abstract

Study objectives: Obstructive sleep apnea (OSA) is accompanied by sleep fragmentation and altered sleep architecture, which can potentially hinder the glymphatic system, increasing risks for Alzheimer's disease (AD), but the status is unclear in OSA. Our aim was to investigate the glymphatic system in OSA subjects and examine the relationships between OSA disease severity, sleep symptoms, and glymphatic system indices in OSA using diffusion tensor imaging (DTI).

Methods: We acquired DTI data from 59 OSA and 62 controls using a 3.0-Tesla MRI and examined OSA disease severity and sleep symptoms with the Pittsburgh Sleep Quality Index (PSQI) and Epworth Sleepiness Scale (ESS). Diffusivity maps in the x-axis (D_xx), y-axis (D_yy), and z-axis (D_zz), as well as in x-y axis (D_xy), y-z axis (D_yz), and x-z axis (D_xz) were calculated, diffusion values for the projection and association fibers extracted, and the DTI analyses along the perivascular space (DTI-ALPS index) were performed. The glymphatic system indices were compared between groups and correlated with disease severity and sleep symptoms in OSA subjects.

Results: D_zz values, derived from projection fiber areas, D_yy and D_zz values from association fiber areas, as well as ALPS and D_yzmean values were significantly reduced in OSA over controls. Significant correlations emerged between disease severity, sleep symptoms, and D_xy, D_xx, and D_zz values in OSA subjects.

Conclusion: OSA patients show abnormal glymphatic system function that may contribute to increased risks for AD. The findings suggest that the APLS method can be used to assess the glymphatic system in OSA patients.

Keywords: DTI-ALPS index; Epworth sleepiness scale; apnea-hypopnea index; diffusion tensor imaging; oxygen desaturation.

Grants and funding

K23 GM132795/GM/NIGMS NIH HHS/United States