AUTHOR=Tsai Cheng-Yu , Wu Sheng-Ming , Kuan Yi-Chun , Lin Yin-Tzu , Hsu Chia-Rung , Hsu Wen-Hua , Liu Yi-Shin , Majumdar Arnab , Stettler Marc , Yang Chien-Ming , Lee Kang-Yun , Wu Dean , Lee Hsin-Chien , Wu Cheng-Jung , Kang Jiunn-Horng , Liu Wen-Te 

TITLE=Associations between risk of Alzheimer's disease and obstructive sleep apnea, intermittent hypoxia, and arousal responses: A pilot study

JOURNAL=Frontiers in Neurology

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2022.1038735

DOI=10.3389/fneur.2022.1038735

ISSN=1664-2295

ABSTRACT=Objectives: 
Obstructive sleep apnea (OSA) may increase the risk of Alzheimer’s disease (AD). However, potential associations among sleep-disordered breathing, hypoxia, and OSA-induced arousal responses should be investigated. This study determined differences in sleep parameters and investigated the relationship between such parameters and the risk of AD. 

Methods: 
Patients with suspected OSA were recruited and underwent in-lab polysomnography (PSG). Subsequently, blood samples were collected from participants. Patients’ plasma levels of total tau (T-Tau) and amyloid beta-peptide 42 (Aβ42) were measured using an ultrasensitive immunomagnetic reduction assay. Next, the participants were categorized into low- and high-risk groups on the basis of the computed product (Aβ42 × T-Tau, the cutoff for AD risk). PSG parameters were analyzed and compared. 

Results: 
We included 36 patients in this study, of whom 18 and 18 were assigned to the low- and high-risk groups, respectively. The average apnea–hypopnea index (AHI), apnea, hypopnea index (during rapid eye movement [REM] and non-REM [NREM] sleep), and oxygen desaturation index (≥3%, ODI-3%) values of the high-risk group were significantly higher than those of the low-risk group. Similarly, the mean arousal index and respiratory arousal index (R-ArI) of the high-risk group were significantly higher than those of the low-risk group. Sleep-disordered breathing indices, oxygen desaturation, and arousal responses were significantly associated with an increased risk of AD. Positive associations were observed among the AHI, ODI-3%, R-ArI, and computed product. 

Conclusions: 
Recurrent sleep-disordered breathing, intermittent hypoxia, and arousal responses, including those occurring during the NREM stage, were associated with AD risk. However, a longitudinal study should be conducted to investigate the causal relationships among these factors.