Summary: Sleep apnea events during REM sleep are linked to verbal memory impairment in older adults at risk for Alzheimer’s disease. The research highlights the importance of focusing on sleep-stage-specific apnea severity for accurate diagnosis and treatment.
Women were found to have more REM-related apnea events, potentially increasing their Alzheimer’s risk. The study underscores the need for personalized sleep apnea assessments to address cognitive decline.
Key Facts:
- REM Sleep Apnea: Higher apnea events during REM sleep correlate with worse verbal memory.
- Sex Differences: Women experience more REM sleep apnea, potentially raising Alzheimer’s risk.
- Personalized Treatment: Focusing on REM-specific apnea events is crucial for accurate diagnosis and treatment.
Source: UC Irvine
A research team led by the University of California, Irvine has revealed the link between the frequency of sleep apnea events during the rapid-eye-movement stage and the severity of verbal memory impairment in older adults at risk for Alzheimer’s disease.
Verbal memory refers to the cognitive ability to retain and recall information presented through spoken words or written text and is particularly vulnerable to Alzheimer’s.
The study, recently published online in the journal Alzheimer’s Research & Therapy, discovered a specific correlation between the severity of sleep apnea – when breathing pauses while an individual is sleeping – and diminished cognition. Higher ratios during REM compared to non-REM stages were associated with worse memory performance.
“Our findings identified the specific features of sleep apnea that are associated with memory, which is important because clinically, events occurring during REM sleep are often overlooked or minimized,” said co-corresponding author Bryce Mander, UC Irvine associate professor of psychiatry & human behavior.
“Most hours of sleep are non-REM, so the overall averages of apnea severity can look much lower than what is typically observed during REM sleep. This means that someone at risk can be misdiagnosed and undertreated because current evaluation standards are not focused on sleep-stage-specific apnea severity.”
“Furthermore,” said co-corresponding author Ruth Benca, professor and chair of psychiatry and behavioral medicine at Wake Forest University School of Medicine, “we found that women are more likely to have a greater proportion of their apneic events in REM sleep in comparison to men, which could potentially be contributing to their greater risk for Alzheimer’s disease.”
The study involved 81 middle-aged and older adults from the Wisconsin Alzheimer’s Disease Research Center with heightened risk factors, of whom 62 percent were female. Participants underwent polysomnography – a comprehensive test that records brain waves, eye movements, muscle activity, blood oxygen levels, heart rate and breathing during sleep – and verbal memory assessments.
Results showed apnea events during REM to be a critical factor contributing to verbal memory decline, especially among individuals with a genetic predisposition to Alzheimer’s and those with a parental history of the disease.
“Our findings highlight the intricate relationship among sleep apnea, memory function and Alzheimer’s risk,” Mander said. “Identifying and addressing REM-specific events are crucial for developing proactive, personalized approaches to assessment and treatment that are tailored to individual sleep patterns.”
The team also included lead author Kitty K. Lui, a graduate student in the San Diego State University/University of California, San Diego joint doctoral program in clinical psychology, and faculty and graduate students from UC Irvine, UC San Diego, the Wisconsin Alzheimer’s Disease Research Center and the University of Kentucky.
Funding: This work was supported by the National Institute on Aging under grants R56 AG052698, R01 AG027161, R01 AG021155, ADRC P50 AG033514, R01 AG037639 and K01 AG068353; by the National Institutes of Health’s Ruth L. Kirschstein National Research Service Award F31 AG048732; and by the National Center for Advancing Translational Sciences’ Clinical and Translational Science Awards Program under grant UL1TR000427.
About this sleep apnea and memory research news
Author: Patricia Harriman
Source: UC Irvine
Contact: Patricia Harriman – UC Irvine
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Older adults at greater risk for Alzheimer’s disease show stronger associations between sleep apnea severity in REM sleep and verbal memory” by Bryce Mander et al. Alzheimer’s Research and Therapy
Abstract
Older adults at greater risk for Alzheimer’s disease show stronger associations between sleep apnea severity in REM sleep and verbal memory
Background
Obstructive sleep apnea (OSA) increases risk for cognitive decline and Alzheimer’s disease (AD). While the underlying mechanisms remain unclear, hypoxemia during OSA has been implicated in cognitive impairment. OSA during rapid eye movement (REM) sleep is usually more severe than in non-rapid eye movement (NREM) sleep, but the relative effect of oxyhemoglobin desaturation during REM versus NREM sleep on memory is not completely characterized. Here, we examined the impact of OSA, as well as the moderating effects of AD risk factors, on verbal memory in a sample of middle-aged and older adults with heightened AD risk.
Methods
Eighty-one adults (mean age:61.7 ± 6.0 years, 62% females, 32% apolipoprotein E ε4 allele (APOE4) carriers, and 70% with parental history of AD) underwent clinical polysomnography including assessment of OSA. OSA features were derived in total, NREM, and REM sleep. REM-NREM ratios of OSA features were also calculated. Verbal memory was assessed with the Rey Auditory Verbal Learning Test (RAVLT). Multiple regression models evaluated the relationships between OSA features and RAVLT scores while adjusting for sex, age, time between assessments, education years, body mass index (BMI), and APOE4 status or parental history of AD. The significant main effects of OSA features on RAVLT performance and the moderating effects of AD risk factors (i.e., sex, age, APOE4 status, and parental history of AD) were examined.
Results
Apnea–hypopnea index (AHI), respiratory disturbance index (RDI), and oxyhemoglobin desaturation index (ODI) during REM sleep were negatively associated with RAVLT total learning and long-delay recall. Further, greater REM-NREM ratios of AHI, RDI, and ODI (i.e., more events in REM than NREM) were related to worse total learning and recall. We found specifically that the negative association between REM ODI and total learning was driven by adults 60 + years old. In addition, the negative relationships between REM-NREM ODI ratio and total learning, and REM-NREM RDI ratio and long-delay recall were driven by APOE4 carriers.
Conclusion
Greater OSA severity, particularly during REM sleep, negatively affects verbal memory, especially for people with greater AD risk. These findings underscore the potential importance of proactive screening and treatment of REM OSA even if overall AHI appears low.
